From MozillaZine Knowledge Base
- The best tutorial is FLOSS manual on Thunderbird. It was a collaborative effort by FLOSS Manuals and Mozilla, originally written for Thunderbird 3.1. It hasn't been updated to reflect all of the user interface changes, but the basics haven't changed, and it covers more features than any others. Introduction to Thunderbird used to have a very popular tutorial but they didn't update it for many years. The link is for an updated (but still incomplete) version based on Thunderbird 17.0 that they are working on.
- If you are using a POP account and want to keep a copy of your messages on the mail server so that they are still accessible via webmail, make certain that there is a checkmark at "Tools -> Account Settings -> Server Settings -> Leave messages on server" before you ever download your mail. It should be set by default if you're using a recent version.
- Thunderbird supports using POP and IMAP mail servers for fetching/reading new messages. It does not support webmail. If you want to use webmail (or WebDAV or HTTPMail) with Thunderbird you normally need to use an add-on that emulates a POP server. It has to do some type of web scrapping (an automated way to read the contents of the screen) to do that, which means it may break if the layout of the web page changes. If that happens you can't use it until an updated version is available. See Using webmail accounts with Thunderbird .
- Thunderbird doesn't provide any way for you to enter the password ahead of time. Instead, when you are prompted for a password there is a checkbox to save the password for the password wizard. If you check that it will automatically enter the password for you next time. If you ever need to change your email providers password you have to do that using webmail (a browser). Thunderbird only saves a copy of the password for its own use, it has no way to change what password your account is supposed to use. After you change your email provider's password delete the saved password using Tools -> Options -> Security -> Passwords -> Saved passwords, exit and restart Thunderbird, and check the checkbox again the next time you are prompted for a password.
- A lot of Thunderbird's functionality is not built-in, and is available though add-ons. The main locations are Mozilla Add-ons (official site), Add-ons mirror (unofficial, despite the name it has many add-ons not on the official web site) and Kaosmos (personal web site of somebody who has developed many add-ons).
- When you install an add-on it checks a maximum version field to see if it supports the current version of Thunderbird. Originally this wasn't an issue since it might take a year for a new major version to be released. However, Mozilla now releases new versions every 6-8 weeks. To avoid problems Thunderbird makes an extension compatible by default if it supports at least version 5, isn't a binary add-on like Lightning or the add-on author explicitly stated they don't want to support that feature.
If you want to use an add-on that doesn't support at least Thunderbird 5.0 install the Disable Add-on Compatibility Checks add-on. It disables version checking. Frequently that will let you use the add-on if it supported at least version 3.0. If the add-on doesn't work uninstall it. If you can't uninstall it, use "help -> restart Thunderbird with add-ons disabled", and then uninstall the add-on. If the add-on works, ignore the warning in the add-on manager about it not being compatible with that version of Thunderbird, its just complaining that you ignored the maximum version field.
- Security in a box guide to installing Thunderbird and the Enigmail extension (OpenPGP).
- How email works (collection of useful articles on e-mail use and hacking)