Email Troubleshooting Tutorial

Email seems simple, but email delivery can fail at any number of places in its journey from the MUA (mail user agent) of the sender to the MUAs of the intended recipients. Delivery may be delayed in a mail queue somewhere in the network cloud, may fail because the email was deleted by a spam filter or rejected for being over file-size limits or having the wrong MIME type content...or the user may be embarrasses to realize that the email that mysteriously vanished is still sitting in their outbox.
Messages sent to mailing lists can be unexpectedly rejected or sent to moderation queues because the sender doesn't understand posting rules, which can vary from list to list and depend on how the sender is classified by each mailing list. Generally, the privilege of direct posting is limited to certain classes of known users to protect the list from spam. Users may think something is wrong when they are unable to post directly to a list when they are actually using a different account from the one under which the posting privileges were granted.
The need to troubleshoot email isn't limited to apparent delivery failure or delays. Sometimes users receive automated email messages they don't understand, or sometimes inappropriate messages get posted to a list.
The existence of so many variables yields so many potential failure points that even though email seems simple in principal, troubleshooting email is an inherently complex process. In the interests of empowering everyone in the online community who would like to understand more about email Support and possibly troubleshoot email themselves, this documentation addresses a wide audience from users experiencing issues when posting to a mailing list to mailing list administrators and site managers. It covers a broad range of topics specific to troubleshooting email but references material scattered throughout the Concepts, Appendix and Tools page help. The purpose of this introduction is to help you get a birds-eye-view of the available documentation, some suggestions as to what might be of most interest to you (depending on whether you are a website user or administrator), plus some pointers that we hope will guide you along the fastest path to the information you need to resolve your issue.