In account setup, the "Incoming user name" might need to be the full email address (e.g. firstname.lastname@example.org). If there is a problem logging in that says "Login to server ... failed", one can put the full username in Account Settings>(the email account)>Server Settings>User Name.
For each account, an outgoing server might need to be added. Go to Tools>Account Settings, and under "Outgoing Server (SMTP)" on the left, add a new server with the server under "Server Name" and the relevant username. Then go to the main account settings and choose the appropriate outgoing SMTP server.
Junk mail Bayesian adaptive training applies to all accounts within a profile. The training is stored in training.dat, for example: "C:\Documents and Settings\[USER]\Application Data\Thunderbird\Profiles\rj22s4cf.default\training.dat"
Spam settings are in Tools>Junk Mail Controls. Under Handling, Check "Move incoming messages determined to be junk mail to:", and select the "Junk" folder. Also, go to "Junk Mail Log" and check "Enable the Junk Mail Log".
To train the junk mail filter, mark messages junk by hitting 'j', and mark messages Not Junk by hitting SHIFT+j. Note that marking an unmarked message as 'Not Junk' does affect the training.dat file.
To make emails available for offline reading in an IMAP account:
- Go to Tools>Account Settings>Offline & Disk Space
- Check "Make the messages in my Inbox available when I am working offline"
- Go to "Select folders for offline use" and select the folders you want
Doing this will store/update a copy of the selected remote folder as an mbox file, which you can only see when working offline.
When messages are deleted, they are immediately deleted from the server's inbox and moved to the Trash folder (both in Thunderbird as well as on the server). When messages are deleted in Thunderbird Trash, they are permanently removed from the server as well.
To copy the Headers of a message, open the message and go to View>Message Source. This opens up the source code, which will have the email headers at the top.