


Have a problem with your Debian mail server? Don't worry, this article provides step-by-step guides to help you diagnose and resolve common failures.
Step 1: Check the service status
First, confirm whether the Postfix and Dovecot mail services are running normally:
sudo systemctl status postfix sudo systemctl status dovecot
If the service is stopped, please start with the following command:
sudo systemctl start postfix sudo systemctl start dovecot
Step 2: Log file analysis
View the log file for error messages:
- Postfix log:
sudo tail -f /var/log/mail.log
- Dovecot log:
sudo tail -f /var/log/dovecot.log
Double-check error messages in the logs, they usually provide clues to the failure.
Step 3: Configuration file check
Check the configuration file for syntax errors:
- Postfix main configuration file:
sudo nano /etc/postfix/main.cf
- Dovecot main configuration file:
sudo nano /etc/dovecot/dovecot.conf
Make sure the configuration file syntax is correct and modify it as needed.
Step 4: DNS Setting Verification
Verify DNS settings, especially MX records and SPF records:
dig MX yourdomain.com dig TXT yourdomain.com
Make sure the MX records point to your mail server and the SPF records are properly configured to prevent spam.
Step 5: Firewall Rule Check
Confirm that the firewall allows mail service ports (usually 25, 465, 587):
sudo ufw status sudo ufw allows 25/tcp sudo ufw allows 465/tcp sudo ufw allows 587/tcp
If necessary, adjust the firewall rules to allow mail traffic.
Step 6: Mail Queue Management
Check and clean up corrupted mail in the mail queue:
sudo postqueue -p sudo postsuper -d ALL
This will display the mail queue status and remove any potentially corrupted messages.
Step 7: User and permission verification
Confirm that the email user exists and the permissions are correct:
sudo getent passwd | grep mailuser sudo chown -R mailuser:mailuser /var/mail/mailuser
Make sure that the email user has the necessary permissions.
Step 8: Send/Receive Test
Use the command line tool to test email sending and receiving:
- Send test email:
echo "Test email" | mail -s "Test" recipient@example.com
- Receive test mail:
mail
This will help you determine if the problem is on the sending or receiving end.
Step 9: System update and service restart
Update the system package and restart the service to apply the changes:
sudo apt update sudo apt upgrade sudo systemctl restart postfix sudo systemctl restart dovecot
Step 10: Seek professional help
If the above steps fail to resolve the issue, please contact your Internet service provider or seek professional mail server support.
Through the above steps, you should be able to effectively diagnose and resolve most Debian mail server failures. Remember, double checking the log files is a key step!
The above is the detailed content of What to do if the debian mail server fails. For more information, please follow other related articles on the PHP Chinese website!

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