Up until last night, my server has been working beautifully (ISPConfig3, Centos 5 etc). However today it appears all incoming mail is getting stuck in the queue and is marked "(temporary failure)". I can't spot anything in the mail logs to identify the problem. How should I go about solving the problem? Mail software: postfix & dovecot. (My users are getting fidgety!) I have restarted postfix, dovecot and amavisd : all started without problem.