Problem: My mail queue is slowly filling. Caused by errors like: Code: temporary failure. Command output: /usr/bin/maildrop: Unable to create a dot-lock at /var/vmail/domain.com/clientID/17623.0.mail.server.com. I've double checked permissions and the pipe to maildrop. Situation: - FirstDomain.com is configured to receive mail for John@FirstDomain.com. All mail for SecondDomain.com should be delivered to FirstDomain.com. A Domain Alias is created for SecondDomain.com. NO other configurations for SecondDomain.com have been made. Mail to Lewis@SecondDomain.com is being accepted for delivery but remains in the queue because maildrop cannot deliver this to the mailbox. Log file reads: Code: Unable to create a dot-lock at /var/vmail/FirstDomain.com/Lewis/12345.0.mail.domain.com The directory /var/vmail/FirstDomain.com/Lewis/ obviously does not exist because the alias 'Lewis' has not been defined. Questions: Why is email for a non-existing alias accepted in the SMTP phase? (This would be EXPECTED behavior) Why is email for Lewis@SecondDomain not delivered to the mailbox of John@FirstDomain.com. (This would be UNWANTED behavior) Can anyone point me in the right direction? Details of setup: ISPConfig: 22.214.171.124 Kernell: Linux post.domain.com 2.6.32-5-amd64 #1 SMP Mon Jan 16 16:22:28 UTC 2012 x86_64 GNU/Linux All packages are fully updated. Other config files or log files available upon request.