How to Solve Amazon SES Relay From EC2 Instance With Postfix on Debian Can't Send Email
How to Solve Amazon SES Relay From EC2 Instance With Postfix on Debian Can’t Send Email
As a data scientist or software engineer, you might find yourself dealing with email delivery issues from your EC2 instances using Postfix on Debian. This blog post is designed to provide a step-by-step guide to troubleshoot and resolve issues when Amazon Simple Email Service (SES) relay from an Amazon Elastic Compute Cloud (EC2) instance with Postfix on Debian can’t send an email.
Step 1: Verify Your Amazon SES and EC2 Settings
Ensure that your Amazon SES service is out of the sandbox mode. In the sandbox mode, you can only send mails to verified email addresses or domains. If you’re still in sandbox mode, you need to request Amazon to move your SES out of it, which can be done via AWS SES Console.
Next, confirm that your EC2’s security group rules allow outbound traffic on port 25, 465, or 587, depending on the port you’re using for your mail transfer agent.
Step 2: Validate Your Postfix Configuration
Check your Postfix configuration to ensure it’s correctly set up to relay emails through Amazon SES. Here is a sample configuration:
relayhost = [email-smtp.us-west-2.amazonaws.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_security_options = noanonymous
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_use_tls = yes
smtp_tls_security_level = encrypt
smtp_tls_note_starttls_offer = yes
The relayhost should point to your Amazon SES SMTP endpoint. The smtp_sasl_password_maps should contain the credentials of your Amazon SES SMTP user.
Step 3: Check Your SASL Password File
Your /etc/postfix/sasl_passwd should look something like this:
[email-smtp.us-west-2.amazonaws.com]:587 YOUR-SES-SMTP-USERNAME:YOUR-SES-SMTP-PASSWORD
Replace YOUR-SES-SMTP-USERNAME and YOUR-SES-SMTP-PASSWORD with your actual Amazon SES SMTP credentials.
After updating the sasl_passwd file, you need to create a hash db file for Postfix by running the following command:
sudo postmap /etc/postfix/sasl_passwd
Step 4: Test Your Email Sending
Now try to send a test email to verify if the email sending is working fine. You can do this using the sendmail command:
echo "Subject: Test Mail" | sendmail -v your-email@example.com
Replace your-email@example.com with your actual email.
Step 5: Check Log Files for Errors
If you’re still not able to send emails, check your mail logs for any errors. You can do this by running:
tail -f /var/log/mail.log
Look for any error messages in the log and take the necessary actions based on the errors.
Conclusion
Troubleshooting Amazon SES relay from EC2 instance with Postfix on Debian can be a complex task. It requires a thorough understanding of Amazon SES, Amazon EC2, and Postfix configurations. However, by following the steps outlined in this guide, you should be able to resolve the issue effectively. If you’re still encountering issues, consider reaching out to AWS Support for further assistance.
Remember, the key to successful email delivery using Amazon SES relay from EC2 instances with Postfix on Debian is correct configuration and proper troubleshooting. Always ensure your settings are correct, and don’t hesitate to consult logs and documentation when things go wrong.
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