Appendix E: Error Messages

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Mail transfer agents (MTAS) are complex systems, and there are thousands of things that go wrong in the process of accepting a message and delivering it locally or remotely. Because qmail was implemented with high reliability as a goal, it's particularly careful in checking for error conditions. Its error messages are generally very descriptive, but sometimes it can be difficult to pinpoint the exact cause of the problem that qmail is complaining about. Rather than attempting to explain each of the hundreds of error messages qmail can generate, this appendix provides some guidance for interpreting these messages.

Error messages can show up in three places: in an interactive shell session, in one of the log files, or in a bounce message.

Interactive Error Messages

Interactive errors are usually the result of "pilot error"-incorrect syntax, permission problems, typographic errors, and so on. First determine whether the error message is coming from the shell or the qmail command you're running. If the message is from a qmail program, consult the man page or Chapter 3 (for user commands) or Chapter 5 (for management commands).

If you run across an error message and you can't figure out what the problem is, try searching the archives of the qmail mailing list. Chances are good that someone has already been there, asked that question, and gotten an answer. The list search engine is at http://www-archive.ornl.gov:8000/.

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