If you are experiencing problems with emails sent from Office 365 not being received by Gmail users, you are not alone. Many businesses encounter issues when it comes to the delivery of emails between these two popular email platforms. This article will guide you through the steps to troubleshoot and resolve any problems you may be facing.
One common issue is emails sent from Office 365 being marked as spam or not being delivered at all to Gmail users. This can be frustrating, especially if you rely on email communication for your business. It is important to understand the factors that may contribute to this problem and take the necessary steps to ensure a smooth email delivery process.
Firstly, it is crucial to check the configuration of your Office 365 email settings. Make sure that your domain is properly authenticated with SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) records. These authentication methods help verify the legitimacy of your emails and increase the chances of them being successfully delivered to Gmail recipients.
Additionally, consider the content of your emails. Gmail’s spam filters are sophisticated and can detect suspicious or spam-like content. Avoid using excessive promotional language or including too many links in your emails. Furthermore, check that your email server’s IP address is not listed on any blacklists, as this can also affect email deliverability.
Common email delivery issues
When using Office 365 and Gmail for sending and receiving emails, there can be certain delivery issues that users may encounter. These issues can arise due to various reasons and can cause inconvenience to the users. Here are some of the common email delivery issues between Office 365 and Gmail:
| Issue | Description |
|---|---|
| Emails not being delivered | In some cases, emails sent from Office 365 to Gmail may not be delivered successfully. This can happen due to incorrect or blocked email addresses, spam filters, or other technical issues. |
| Emails going to spam folder | Gmail’s spam filters can sometimes mark legitimate emails from Office 365 as spam, causing them to be redirected to the recipient’s spam folder instead of the inbox. This can lead to important emails being missed or overlooked. |
| Delay in email delivery | There may be instances where emails sent from Office 365 to Gmail experience a delay in delivery. This delay can happen due to network congestion, server issues, or other factors affecting the email routing. |
| Email formatting issues | When emails are sent from Office 365 to Gmail, there can be instances where the formatting or layout of the email is altered. This can occur due to differences in the way each email client interprets and displays HTML content. |
| Attachments not being received | Sometimes, attachments sent from Office 365 to Gmail may not be received by the recipient. This can happen due to file size limitations, restrictions imposed by the email client, or other technical issues. |
It is important to address these email delivery issues promptly to ensure smooth communication between Office 365 and Gmail users. By understanding the common problems and their underlying causes, appropriate measures can be taken to resolve or mitigate them.
Understanding SPF and DKIM
Sending and receiving email can sometimes be a complex process, especially when it comes to configuring email services like Office 365 and Gmail. One common issue that users may encounter is emails not being delivered or received properly.
One of the key factors that can affect email delivery is the authentication of the email sender. SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) are two widely used email authentication methods that can help to ensure the security and reliability of email communication.
SPF allows the email recipient’s server to verify that the email was actually sent from an authorized server. It works by checking the SPF record, which is a DNS record that specifies the authorized mail servers for a given domain. If the sending server is not listed in the SPF record, the recipient’s server may reject the email or mark it as spam.
DKIM, on the other hand, uses cryptographic signatures to verify the authenticity and integrity of the email. It works by adding a digital signature to the email headers. The recipient’s server can then verify this signature by checking the corresponding DKIM public key in the DNS records of the sender’s domain. If the signature is not valid, the email may be rejected or flagged as suspicious.
Understanding SPF and DKIM is crucial for resolving email delivery issues between Office 365 and Gmail. By properly configuring SPF and DKIM for your domain, you can increase the chances of your emails being delivered successfully and prevent them from being marked as spam.
In conclusion, SPF and DKIM are important email authentication methods that help to ensure the security and reliability of email communication. By implementing these techniques, you can improve your email deliverability and avoid issues with not receiving emails from Office 365 or Gmail.
Importance of correct DNS settings
Proper configuration of DNS settings is crucial in ensuring smooth email delivery between Gmail and Office 365. DNS, or Domain Name System, is responsible for translating domain names into IP addresses, which allows email servers to communicate with each other effectively.
When it comes to sending and receiving emails between Gmail and Office 365, the DNS settings play a vital role. These settings include MX (Mail Exchanger) records, SPF (Sender Policy Framework), and DKIM (DomainKeys Identified Mail) records, which need to be properly configured for both Gmail and Office 365.
MX Records
MX records specify which email servers are responsible for receiving emails for a particular domain. It is important to verify that MX records are correctly set up for both Gmail and Office 365. This ensures that emails sent from Gmail to Office 365, and vice versa, are directed to the correct email servers, without any delivery issues.
SPF and DKIM Records
SPF and DKIM records are authentication mechanisms that help prevent email spoofing and increase the chances of successful email delivery. SPF records specify which servers are authorized to send emails on behalf of a domain, while DKIM records validate the authenticity and integrity of the email message.
When Gmail receives an email from Office 365, it checks the SPF and DKIM records to verify the legitimacy of the email. If these records are not correctly configured, Gmail may mark the email as suspicious or reject it altogether. Similarly, incorrect SPF or DKIM records in Office 365 may result in Gmail flagging the emails sent from Office 365 as spam.
In conclusion, having the correct DNS settings, including MX records, SPF records, and DKIM records, is essential for ensuring smooth email delivery between Gmail and Office 365. Proper configuration of these records helps prevent delivery issues and reduces the chances of emails being marked as spam.
Sender reputation and email deliverability
Emails sent from Office 365 might sometimes not reach their recipients who use Gmail. This can be due to various reasons, one of which is the sender reputation.
Sender reputation plays a crucial role in determining whether emails are delivered or not. Email providers like Gmail analyze the sender’s email practices and assign a reputation score based on factors such as email volume, engagement, and spam complaints.
If your emails are not reaching Gmail users, it is possible that your sender reputation has been negatively affected. This can happen if your emails are frequently marked as spam or if there are issues with your email authentication setup.
To improve email deliverability to Gmail recipients, consider taking the following steps:
- Authenticate your email domain: Implement Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC) protocols to verify the authenticity of your emails.
- Monitor your email volume: Sending a high volume of emails in a short period of time can raise suspicions. Gradually increase your email volume to build a positive sender reputation.
- Send engaging content: Emails that receive high open rates and engagement are more likely to be delivered. Craft relevant and personalized content that resonates with your recipients.
- Manage customer complaints: Promptly address any complaints or unsubscribe requests. This helps maintain a good sender reputation and avoids potential spam complaints.
By paying attention to your sender reputation and implementing best practices for email deliverability, you can increase the chances of your Office 365 emails reaching Gmail users successfully.
Configuring SMTP relay
If you are experiencing issues with receiving emails between Office 365 and Gmail, it may be necessary to configure SMTP relay. SMTP (Simple Mail Transfer Protocol) relay allows the transfer of emails between different email servers.
In order to configure SMTP relay for Office 365 and Gmail, you will need to follow these steps:
- 1. Log in to your Office 365 account and navigate to the Exchange Admin Center.
- 2. Go to the Mail Flow section and click on “Connectors”.
- 3. Click on the “New” button to create a new connector.
- 4. Select “From Office 365” and “To Partner organization” as the options for the connector.
- 5. Provide a name for the connector and click “Next”.
- 6. In the next step, select “Only when I have a transport rule set up that redirects messages to this connector” and click “Next”.
- 7. Add the Gmail domain by clicking on the “+” button and entering the domain name.
- 8. Click “Next” and then “Finish” to complete the connector setup.
After configuring the SMTP relay, emails between Office 365 and Gmail should now be delivered properly. If you are still experiencing any issues, make sure that the SMTP relay is properly set up and that there are no restrictions or filters in place that may prevent the delivery of emails.
Troubleshooting email bounces
If you are experiencing issues with emails not being received from Office 365 to Gmail or vice versa, you may be encountering email bounces. Email bounces occur when an email is rejected or undeliverable by the recipient’s email server.
When troubleshooting email bounces between Office 365 and Gmail, here are some common causes and solutions to consider:
1. Incorrect email addresses: Double-check that the email addresses you are sending from and to are accurate. Typos or misspellings can lead to delivery failures.
2. Spam or junk filters: Check the spam or junk folders in both Office 365 and Gmail. Sometimes, legitimate emails can be mistaken as spam and end up in these folders. Marking the email as “not spam” can help prevent this issue in the future.
3. Blacklisting: Ensure that neither your email server (Office 365) nor the recipient’s email server (Gmail) is on any blacklists. Blacklisting can occur if the servers have been flagged for sending spam or engaging in other malicious activities. You can use online tools to check if your server is blacklisted and take appropriate actions to resolve the issue.
4. DMARC, SPF, and DKIM settings: Review your DMARC, SPF, and DKIM settings for both Office 365 and Gmail. These settings help authenticate your email and prevent spoofing and phishing attacks. Make sure the settings are configured correctly and aligned between the two email services.
5. Network or server issues: Network or server issues at either end (Office 365 or Gmail) can cause email delivery problems. Check for any reported outages or disruptions in service and contact the respective support teams for assistance.
By addressing these common causes, you can troubleshoot and resolve email bounce issues between Office 365 and Gmail. Remember to double-check email addresses, review spam filters, check for blacklisting, verify DMARC/SPF/DKIM settings, and investigate network or server issues to ensure smooth email delivery.
Handling email filtering and spam folders
When it comes to email delivery between Gmail and Office 365, one common issue that users encounter is emails not being delivered or ending up in spam folders. This can be frustrating and can lead to missed important messages.
Gmail and Office 365 have different filtering and spam detection mechanisms in place. Sometimes, legitimate emails from Office 365 may be mistakenly identified as spam by Gmail. To prevent this from happening, there are a few steps you can take.
1. Whitelisting Office 365 emails
To ensure that emails from Office 365 are not marked as spam by Gmail, you can add the sender’s email address or domain to your Gmail whitelist. This will tell Gmail to always deliver emails from that particular sender or domain to your inbox.
2. Checking the spam folder
If you notice that emails from Office 365 are consistently ending up in the spam folder, you should regularly check the spam folder and mark those emails as “not spam”. This will help train Gmail’s spam filter and improve the delivery of Office 365 emails to your inbox.
It’s also important to periodically review the spam folder to ensure that no legitimate emails are getting caught in the spam filter. If you find any important emails in the spam folder, make sure to move them to your inbox or mark them as “not spam”.
By taking these steps, you can improve the email delivery between Gmail and Office 365, ensuring that important emails are not missed or lost in spam folders.
| Gmail | Office 365 |
|---|---|
| Filtering mechanisms | Filtering mechanisms |
| Spam detection | Spam detection |
| Whitelisting | N/A |
Managing email attachments and file size limitations
When sending emails between Office 365 and Gmail, it is important to be aware of the limitations and restrictions regarding email attachments and file sizes. Failure to consider these limitations may result in emails not being received or attachments not being accessible.
Both Office 365 and Gmail have maximum attachment size limits. Office 365, for example, has a default attachment size limit of 25 MB for Outlook and Exchange online. Gmail, on the other hand, has a maximum attachment size limit of 25 MB for incoming mail and 35 MB for outgoing mail.
If you try to send an attachment that exceeds these limits, you may encounter issues such as the email not being delivered, bounced back, or the attachment not being accessible by the recipient.
To manage these limitations and ensure successful delivery of emails with attachments, consider the following tips:
| Tip | Description |
|---|---|
| 1 | Compress attachments: Reduce the file size of the attachment by compressing it into a ZIP file. This can help minimize the file size and make it within the allowable limits of both Office 365 and Gmail. |
| 2 | Use file sharing services: Instead of attaching large files directly to the email, upload them to a file sharing service and include a link in the email. This allows the recipient to download the file from the service, eliminating the attachment size limitations. |
| 3 | Consider alternative methods: If the attachment is too large to be sent via email, consider using alternative methods such as FTP or file transfer services. These methods are specifically designed for transferring large files and can bypass the attachment size limitations. |
By considering these tips and managing the limitations of email attachments and file sizes, you can ensure that your emails between Office 365 and Gmail are successfully delivered and that attachments are accessible to the recipients.
Preventing email spoofing and phishing attacks
Email spoofing and phishing attacks are common techniques used by cybercriminals to deceive recipients and gain unauthorized access to personal information. These attacks can be highly damaging to individuals and organizations, as they often trick users into revealing sensitive information or performing malicious actions.
Gmail’s robust security measures help prevent email spoofing and phishing attacks. Gmail uses advanced algorithms to identify and filter out suspicious emails, keeping users protected. However, it’s essential to stay cautious and take additional steps to safeguard yourself and your organization against these threats.
Here are a few best practices to prevent email spoofing and phishing attacks:
1. Enable two-factor authentication (2FA)
By enabling 2FA, you add an extra layer of security to your Gmail account. This feature requires users to provide an additional verification method, such as a verification code sent to their mobile device, along with their login credentials. It significantly reduces the risk of unauthorized access to your account, even if someone manages to obtain your password.
2. Be cautious of suspicious emails
Exercise caution when receiving emails from sources you’re not familiar with or emails that appear suspicious. Check the sender’s email address carefully, as phishers often use similar-looking email addresses to trick recipients. Avoid clicking on any suspicious links or downloading attachments from unknown sources.
3. Regularly update your security software
Keep your security software, antivirus, and anti-malware programs up to date on all your devices. These software solutions help detect and mitigate potential threats, including phishing attempts and malicious attachments.
4. Educate yourself and your team
Stay informed about the latest phishing tactics and educate yourself and your team about email security best practices. Regularly train employees on how to identify phishing attempts, the importance of strong passwords, and how to report suspicious emails.
By following these practices and staying vigilant, you can significantly reduce the risk of falling victim to email spoofing and phishing attacks.
Impact of email client settings on deliverability
The way email clients are configured can have a significant impact on email deliverability between Office 365 and Gmail. This is because each email client has its own set of rules and settings that determine how incoming emails are handled.
In some cases, emails sent from Office 365 may not reach Gmail recipients due to certain client settings. For example, if the email client is configured to automatically filter out emails from unknown senders or mark them as spam, legitimate emails from Office 365 may end up in the spam folder or even be blocked entirely.
To ensure that emails from Office 365 are delivered to Gmail recipients, it is important to review and adjust the settings of the email client. This may include whitelisting the domain or email address of the sender, disabling aggressive spam filtering, or adjusting the sensitivity of the spam filter.
Additionally, it is important to note that emails received from Office 365 may not always appear in the inbox. Some email clients categorize incoming emails into different tabs or folders based on their content or sender. Therefore, it is recommended to check other tabs or folders, such as the Promotions or Updates tab, to ensure that emails from Office 365 are not missed.
In summary, the email client settings play a crucial role in the deliverability of emails between Office 365 and Gmail. By reviewing and adjusting these settings, recipients can ensure that important emails from Office 365 are not missed and are delivered to the appropriate inbox folder.
Setting up email forwarding and aliases
If you find that you are not receiving emails from Gmail to your Office 365 account, there are a few steps you can take to fix this issue. One option is to set up email forwarding and aliases.
Email forwarding allows you to automatically forward any incoming emails from your Gmail account to your Office 365 account. This ensures that you receive all emails sent to your Gmail address in your Office 365 inbox. To set up email forwarding, follow these steps:
Step 1:
First, log in to your Gmail account and go to the settings menu. From there, navigate to the “Forwarding and POP/IMAP” tab.
Step 2:
Click on the “Add a forwarding address” button and enter your Office 365 email address. Gmail will send a verification email to your Office 365 account to confirm the forwarding setup.
Step 3:
Log in to your Office 365 account and open the verification email from Gmail. Follow the instructions provided to complete the email forwarding setup.
Email aliases allow you to send and receive emails using different email addresses from within your Office 365 account. This can be useful if you want to separate different types of emails or create a more professional email address. To set up email aliases, follow these steps:
Step 1:
In your Office 365 account, navigate to the settings menu and select “Options.” From there, go to the “Mail” section and click on “Email aliases.”
Step 2:
Click on the “Add an alias” button and enter the email address you want to use as an alias. You can choose whether the alias is an email address within your Office 365 domain or an external email address.
Step 3:
Once you’ve added an alias, you can select it as the “From” address when composing or replying to emails in your Office 365 account.
By setting up email forwarding and aliases, you can ensure that you receive all necessary emails in your Office 365 account, even if they are not sent directly from Gmail. This can help you stay organized and streamline your email management.
Configuring email routing rules
When emails are not being received from Office 365 to Gmail, it may be necessary to configure email routing rules. These rules define how emails should be handled and routed between the two email systems.
To start configuring the email routing rules, log in to the Office 365 Admin Center and navigate to the Exchange admin center. From there, select the mail flow option and click on the connectors tab.
Next, click on the plus (+) icon to create a new connector. Choose the “From Office 365” option as the source and the “To Gmail” option as the destination. This ensures that emails sent from Office 365 will be routed correctly to Gmail.
In the configuration settings for the connector, specify the domain or email addresses that are not receiving emails from Office 365 to Gmail. This ensures that the routing rule is applied only to the specified emails. Additionally, ensure that the connector is set to prioritize the routing of these emails.
Once the configuration settings are complete, save the connector and test the email delivery between Office 365 and Gmail. Monitor the email flow to ensure that the desired emails are now being received properly.
By configuring email routing rules, it is possible to resolve issues with emails not being received from Office 365 to Gmail. These rules help to ensure that emails are properly routed between the two email systems, improving overall communication and delivery reliability.
Overcoming blacklisting issues
One common issue that can occur when sending emails from Office 365 to Gmail is being blacklisted. Blacklisting happens when the IP address from which the emails are being sent is flagged as spam by Gmail. This can result in emails sent from Office 365 not being delivered or ending up in the recipient’s spam folder.
To resolve blacklisting issues, you can take the following steps:
1. Check the reputation of your IP address: Use online tools like MXToolbox or BarracudaCentral to verify if your IP address is blacklisted. If it is, contact your email service provider to find out the reason and request removal from the blacklist.
2. Monitor email sending practices: Make sure you are following best practices for email sending and minimizing the chances of being flagged as spam. This includes avoiding sending bulk emails, maintaining a good sender score, and adhering to email authentication protocols like SPF, DKIM, and DMARC.
3. Stay updated on Gmail’s guidelines: Familiarize yourself with Gmail’s sending guidelines and policies to ensure your emails comply with their standards. This will help minimize the risk of being flagged as spam or blacklisted.
4. Use a reputable email delivery service: Consider using a third-party email delivery service or SMTP relay to send your emails. These services often have better deliverability rates and can help you sidestep blacklisting issues.
By taking these steps, you can improve the chances of your emails from Office 365 being successfully delivered to Gmail accounts and reduce the likelihood of blacklisting issues.
Best practices for email troubleshooting
When it comes to troubleshooting email delivery issues between Office 365 and Gmail, there are some best practices you can follow to ensure smooth communication:
| Problem | Solution |
|---|---|
| Office 365 emails not receiving in Gmail | Check the spam folder in Gmail for any emails that might have been incorrectly marked as spam. If the emails are not in the spam folder, ensure that the sender’s email is not blocked or blacklisted in Gmail. |
| Emails from Gmail not receiving in Office 365 | Make sure the sender is using the correct email address and that there are no typos or misspellings. If the issue persists, check the junk email folder in Office 365 for any falsely identified emails. |
| Missing emails between Office 365 and Gmail | Confirm that the emails were sent successfully by checking the sent items folder in the respective email provider. If the emails are missing, it might be a temporary server issue. Give it some time and try again later. |
| Incorrect formatting or display of emails | Ensure that the emails are being sent in a compatible format. Avoid using advanced formatting options that might not be supported by both Office 365 and Gmail. If the issue persists, consider using plain text emails instead of HTML. |
By following these best practices, you can effectively troubleshoot and resolve any email delivery issues between Office 365 and Gmail, ensuring uninterrupted communication.
Working with third-party email service providers
When using Office 365 and Gmail, it is important to understand how third-party email service providers handle email delivery. In some cases, emails sent from Office 365 might not reach Gmail recipients, or emails sent from Gmail might not reach Office 365 recipients. This can be due to various factors, such as spam filters, email authentication issues, or configuration settings.
If you are experiencing email delivery issues between Office 365 and Gmail, working with third-party email service providers can help address the problem. These providers specialize in managing and delivering emails, and they can provide insights and solutions to ensure that your emails are successfully delivered.
Here are some steps to take when working with third-party email service providers:
- Contact your third-party email service provider and explain the issue you are experiencing. Provide them with specific details, such as the email addresses involved, the date and time of the issue, and any error messages you received.
- Ask your email service provider to check their logs and investigate the issue. They should be able to determine if there are any issues on their end that could be causing the problem.
- Work with your email service provider to implement any recommended solutions or changes to your email configuration. This might involve adjusting spam filter settings, configuring email authentication methods like SPF and DKIM, or resolving any issues with your DNS records.
- Monitor the email delivery after making the necessary changes. Keep an eye on any bounce-back messages or delivery failures to ensure that the issue has been resolved.
By working closely with your third-party email service provider, you can make sure that emails sent from Office 365 reach Gmail recipients and vice versa. Remember to maintain open communication and follow up to ensure that the issue is fully resolved.
Maintaining email deliverability over time
Ensuring that your emails are consistently reaching their intended recipients is critical for effective communication. It is important to regularly monitor and maintain email deliverability, especially when using Office 365 and Gmail as your email platforms.
Here are some steps you can take to maintain email deliverability over time:
1. Monitor bounce rates
Bounce rates indicate the percentage of emails that were not successfully delivered to the intended recipients. By regularly monitoring bounce rates, you can identify any issues with email delivery and take appropriate actions to address them. Office 365 and Gmail provide tools for tracking bounce rates and analyzing the reasons behind the bounces.
2. Keep your sender reputation high
Gmail and Office 365 use sender reputation as a factor in determining whether to deliver an email to the recipient’s inbox or spam folder. To maintain a high sender reputation, it is important to follow best practices for email marketing, such as sending relevant and engaging content, avoiding spam trigger words, and keeping your email list clean.
3. Authenticate your emails
Both Gmail and Office 365 support email authentication protocols like SPF, DKIM, and DMARC. These protocols help verify the authenticity of your emails and prevent spoofing or phishing attempts. By properly configuring these authentication protocols, you can improve email deliverability and protect your sender reputation.
4. Regularly review your email sending practices
It is important to review and update your email sending practices regularly. This includes keeping your contact lists up to date, removing inactive or unengaged subscribers, and optimizing your email templates for different devices and email clients. By staying proactive, you can improve the chances of your emails reaching the recipients’ inboxes.
By following these best practices, you can maintain a high level of email deliverability between Office 365 and Gmail over time. Regular monitoring, reputation management, authentication, and reviewing your sending practices are key to ensuring that your emails are not only received but also engage your recipients effectively.
Question-answer:
Why are my emails from Office 365 not getting delivered to Gmail?
There could be several reasons why emails from Office 365 are not getting delivered to Gmail. One possible reason is that the emails are being marked as spam by Gmail’s spam filters. Another reason could be an issue with the email routing configuration between the two systems. It’s also possible that there could be an issue with the DNS records for your domain. To fix this issue, you can check the spam folder in Gmail to see if the emails are being marked as spam, contact your email administrator to check the email routing configuration, and verify the DNS records for your domain.
What can I do if my emails from Gmail are not being delivered to Office 365?
If your emails from Gmail are not being delivered to Office 365, there are a few things you can try to fix the issue. First, you can check the spam folder in Office 365 to see if the emails are being marked as spam. If they are, you can mark them as not spam to prevent future emails from being filtered. You can also check the email routing configuration in Office 365 to ensure that the emails are being routed correctly. Finally, you can contact Gmail support to see if there are any known issues with email delivery to Office 365.
How can I prevent my emails from Office 365 from being marked as spam by Gmail?
To prevent your emails from Office 365 from being marked as spam by Gmail, there are a few things you can do. First, make sure that your email content is not overly promotional or spammy. Avoid using excessive capitalization, exclamation marks, and misleading subject lines. You can also ask your recipients to add your email address to their contacts or whitelist your email domain. Additionally, you can set up DKIM (DomainKeys Identified Mail) and SPF (Sender Policy Framework) authentication for your domain to improve email deliverability.
Why is there a delay in email delivery between Office 365 and Gmail?
There can be several reasons for a delay in email delivery between Office 365 and Gmail. One possible reason is that there is a high volume of emails being processed, causing a backlog in the email servers. Another reason could be network congestion or latency issues between the two email systems. In some cases, the delay may be intentional, such as when Gmail is performing additional checks on incoming emails for security reasons. If the delay is persistent and causing significant issues, you can contact the support teams for both Office 365 and Gmail to investigate and resolve the issue.
What should I do if my emails are being rejected by Office 365 or Gmail?
If your emails are being rejected by Office 365 or Gmail, there are a few things you can do to troubleshoot the issue. First, check the bounce message or error code that you receive when the email is rejected. This can provide information about why the email was rejected. Common reasons for rejection include blacklisted IP addresses, exceeded email sending limits, or invalid email addresses. Once you have identified the reason for rejection, you can take appropriate action such as removing your IP address from any blacklists, adjusting your email sending limits, or correcting any invalid email addresses.