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Troubleshooting Emails when sending messages to Gmail

When running an email server, it is very important to make sure your server is properly configured. Failure to do so will result in your IP address being blacklisted, which can result in email delivery failures. If you are having issues sending outbound emails to Gmail, there could be some configuration issues on your end.

Gmail has recently put out certain restrictions when sending emails to them, which resulted in many senders having issues with message delivery to Gmail. They have put out guidelines on best practices for sending an email to Gmail. Here are the important points listed below:

1. Use TLS/SSL
Enable Transport Layer Security (TLS) for secure communication between email servers. This ensures that the data exchanged during the email transmission is encrypted. This helps in verifying the authenticity of your email server and prevents potential man-in-the-middle attacks.

To use TLS, a valid SSL certificate is required. You can obtain a certificate from a Certificate Authority (or CA), or use a free certificate from Let's Encrypt.
2. Setup SPF, DKIM, and DMARC
SPF DKIM and DMARC are protocols that are used to fight against spoofing, a mechanism spammers use to forge emails to pretend they came from the actual address. Here are the different types of protocols listed below:

Sender Policy Framework (SPF): SPF prevents forgery by designating a handful of IP addresses where emails can originate for your domain. SPF check will fail if a spammer sends a forged message from their IP, allowing email servers to treat that as spam.

DomainKeys Identified Mail (DKIM): DKIM ensures the message was composed by someone belonging to the domain they claim to be part of. Additionally, it ensures the message is not modified in transit. Technically, the message is digitally signed by the email server before leaving and this signature is verified by the receiving end, allowing the receiving end to verify the authenticity of the message.

Domain-based Message Authentication, Reporting, and Conformance (DMARC): DMARC builds on top of SPF and DKIM. This not only helps prevent forgery but also provides a sophisticated reporting mechanism allowing the senders to fine-tune their SPF and DKIM rules.

Setting the above authentication methods require you to create a TXT record for your domain. Xeams can create SPF and DKIM txt records, as well as guidelines on implementing DMARC. Please see here for additional details.
3. Prevent Spam Rate Below 0.1%
Gmail has a tool to check ownership of your domain. Please check here for more details.

This tool also displays information such as the percentage of your email marked as spam by the user and delivery errors. It's important to keep the spam rate below 0.1% to prevent your server from being blacklisted.
4. Format Messages correctly
RFC (Request for Comments), is a formal document that contains technical specifications and organizational notes for the Internet. Emails must follow the formatting standards outlined in RFC 5322. Following these standards ensures compatibility and consistency across different email clients and servers.

For example, make sure every message includes a valid Message-ID. More information about RFC 5322 can be found here.

If your messages are in HTML, format them according to the HTML Standards here. For example, don't use HTML and CSS to hide content in your messages. Hiding content might cause messages to be marked as spam.
5. IP Address MUST Have PTR Record
A PTR record, or a reverse DNS record, is a type of record that is used for validation. While a regular DNS record resolves a domain name to an IP address, PTR does the opposite. It resolves an IP address to a domain name.

For example, if you have an MX record, myemail.mydomain.com, that points to 11.12.13.14, then a PTR record has the value 11.12.13.14 that points to myemail.mydomain.com.

PTR records help SMTP servers verify that the IP address of the sending server connects to a legitimate domain name. This helps prevent email spoofing. A PTR record goes into an ISP's DNS server. Therefore, you will need to consult with your ISP to add this record, since they are the one who owns the IP Address. Xeams can check if your PTR record is valid. Please see here for more details.
6. Validate Email Configuration
Once you have all the necessary configurations done, confirm these settings are valid. You can check these settings by either looking up DNS TXT records, such as running the nslookup command in command prompt, or go to online email validation checks.

In Xeams, there are a couple of methods to check configuration. In the web interface, go to Tools, then click on Diagnostic check - Outbound. This will run a test to confirm outbound settings, including reverse IP lookup, and DMARC, are correctly configured.

Another method is to send an email to validate.server@synametrics.com with the word validate in the subject line. Once sent, you will get a reply back with a report that shows a grade on how well-configured your email server is. For more information, please check here.

PTR records help SMTP servers verify that the IP address of the sending server connects to a legitimate domain name. This helps prevent email spoofing. A PTR record goes into an ISP's DNS server. Therefore, you will need to consult with your ISP to add this record, since they are the one who owns the IP Address. Xeams can check if your PTR record is valid. Please see here for more details.

Conclusion

To combat malicious or spam emails, many email servers, including Gmail, and Hotmail, are increasing their security. These include mechanisms to prevent forgery, and using the latest TLS. Additionally, emails must follow the correct RFC protocol and the correct HTML formats. Adhering to the guidelines that Gmail has published will ensure your emails will correctly be delivered to them. Xeams has tools that ensure your outbound emails flow correctly to Gmail.


Created on: Mar 7, 2024
Last updated on: Jul 19, 2024

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