In my work I often receive problem reports from clients regarding their email service, here is some advice to help get the problem fixed as fast as possible:
Firstly problems sending mail and problems receiving mail are often unconnected and should be reported separately. If only one aspect of a problem is reported then probably only one will be fixed… Also receiving mail via POP or IMAP is separate to the mail transfer process.
For problems on mail transfer the following points should be addressed in any report to increase the speed of problem resolution. Don’t think of this as being for the benefit of the person who fixes your mail server, think of it as being for your own benefit in getting your email working again rapidly.
Make sure that every complaint has a specific example. Saying “email doesn’t work for everyone” is not helpful, often when investigating some complaints I discover that email works for many people. Saying “email doesn’t work for John Smith and other people report problems too” is helpful, I can investigate John’s problem while knowing that it’s a symptom of a larger problem.
For every report make sure that you list a sender and recipient email address for an instance of the problem. Saying that “firstname.lastname@example.org can’t send mail to email@example.com” is much more useful than saying “firstname.lastname@example.org can’t send mail to some people“.
Whenever possible make sure that the problem can be reproduced by the person who is making the report. A report such as “John Smith can’t send email from his PC” is not nearly as helpful as “I can’t send email from my PC“, the reason is that I often require more information from the person who experienced the problem and going through a third-party slows things down.
Make a careful note of the time of the problem. If you report that email@example.com can’t send mail to firstname.lastname@example.org and the logs show that such a message was correctly delivered at 9AM I will assume that the problem was mistakenly reported and not that maybe there was a problem which first occurred at 9:30AM.
When noting the time make sure you note any discrepancies. If a problem occurs at 9AM and a bounce message reports a problem occurring at 10AM then please make sure to note both times when reporting the problem. Either or both times could be referenced in the log files and the more information you provide the better the chance that the problem will be fixed quickly.
Most serious errors in email delivery have a code numbered from 550 to 559 with an error message. Any time you see a bounce message which includes text such as “Remote host said: 554” then please report all the rest of the text on that line, it will often tell me precisely what needs to be done to fix the problem.
Any time a bounce or other error message includes a URL then please report it to me. Sometimes it takes me a significant amount of work to discover what I could have learned in a matter of seconds if I had the URL.