From MozillaZine Knowledge Base
This article suggests ways to to keep Thunderbird working well and avoid serious problems. It is mainly intended for new users, so ideas are presented simply, with few alternatives and choices. The assumption is when you get more experience you may do things differently as you understand the tradeoffs.
- Check that your antivirus software isn't configured to delete your Inbox if you get a virus. If it doesn't support quarantining infected messages, see this article for a workaround.
- Don't check for viruses in messages you send. This avoids interoperability problems. And if the recipient isn't already using a anti-virus program, then they have bigger problems to worry about than your message.
- Don't keep a copy of your messages on the POP server without providing some way to automatically get rid of them later. If you use "Tools -> Account Settings -> Server Settings -> Leave message on server" to keep a copy of the original message on the POP server after Thunderbird checks for new mail (so that you can still access it via webmail), then you should set the number of days it should keep the copy.
- If you want to use an addon that is not compatible with your version of Thunderbird, try installing the Disable Add-on Compatibility Checks add-on first, to disable version checking. That will let you install it, though its possible the add-on won't work because of an API change, or may work but have bad side effects. Tools -> add-on will complain that the add-on is incompatible with the current version of Thunderbird, but you can ignore that warning. If the add-on doesn't work or causes problems, disable or uninstall the add-on using Tools -> Add-ons. If you can't do that, use "Help -> Restart with add-ons disabled" to start Thunderbird in safe mode and then uninstall the add-on.
All add-ons have a maximum version field that specifies the last supported version of Thunderbird. Some add-on authors don't update their add-ons often enough to keep the version information current. However, if the add-on supports at least version 10 of Thunderbird and doesn't have binary components (like Lightning and Enigmail do) it should be "compatible by default".
- Keep the Inbox empty. Move new messages that you want to keep to another folder after you've read them. This may help avoid corrupting your Inbox folder, and will help maintain best performance.
- Regularly empty your Junk Folder and your Trash folder.
- Regularly compact your Inbox folder and any folders from which you delete messages in or move messages. Once a week is a useful rule of thumb, though how often you do this depends upon how many messages you get and how critical they are to you. Ideally you would configure Thunderbird to automatically compact folders for you by setting it to compact when it will save 75KB (or another low value) and not prompt you for permission to compact the folders. For further information on these settings, see the Compacting folders article.
- Regularly back up your profile. As a minimum back up your entire profile once you get Thunderbird working. Mozbackup is a very popular way to backup a profile if you're using Windows. Its simple to use (you don't even have to know where your profile is stored) and doesn't require you to know how to install an add-on. However, its not as reliable as it used to be. Use the beta version mentioned in the News section on its web page, not the released version. Later on consider using the ImportExportTools add-on instead as it supports backup scheduling and is actively maintained.
- Make sure you have enough unused disk space for Thunderbird to store additional messages and create temporary files etc. Its a good idea to try to keep at least 10% of your hard disk empty to avoid performance problems. Both the profile and the program are normally stored on the boot drive (under Windows). If you are running short of space see Moving your profile for how to move it to another drive. If you are running Windows periodically defragment the hard disk ("Disk Defragmenter" in "All Programs -> Accessories -> System Tools" in the Start Menu).
Add-ons and upgrading
- Only install extensions from Mozilla add-ons and Kaosmos. Not every extension is well behaved. These are the two most popular web sites for Thunderbird extensions, thus there is a better chance an extension has been tested and/or used by a lot of other users.