We run into a problem where customers Linux vm was sending a lot of unwanted messages. In order to troubleshoot this problem we did 2 things. Instructions below are for CentOS 6 and 7 but will also work on other distributions with minor configuration changes.
1. Check system for open relay with telnet from network that is not on my network list.
telnet "mailsrv" 25 ehlo test.test.com mail from:email@example.com rcpt to: firstname.lastname@example.org "some email address that is not local or in the transport list"
You should get relay denied message. If you did not your system us an open relay and unless it is intended to be one, you need to address this ASAP.
2. If the system is not open relay we need to determine which php script is sending mail.
mail.add_x_header = On mail.log = /var/log/phpmail.log
Now create log file.
touch /var/log/phpmail.log chown apache:apache /var/log/phpmail.log
All done. Now just monitor log file for after you restart apache
service httpd restart tail -f /var/log/phpmail.log
1. Check the mail queue with command mailq
2. Copy the first column of the mail queue which shows unique mail ID’s – make sure it is one of the spam emails
3. Run the following command
postcat -q ID_OF_MESSAGE
4. Find line starting with “X-PHP-Originating-Script”. This should show which script is generating the spam emails.
After you find the script you can remove it , patch your server and clear your queue.
mailq # view messages in the queue postsuper -d ALL # clear the queue