re: The IMAP machines will erase downloaded messages from the server. Unfortunatley I cannot find the setting to leave these messages on the server.

IMAP mail accounts see a remote view of the emails in folders on the server. You subscribe to see folders and headers are downloaded. When you click to read an email, a copy of the folder is downloaded to a temporary file to facilitate quicker access. If you sychronise subscribed folders then a copy is downloaded to the Thunderbird Profile, but this folder is constantly updated to match the server. If you delete any emails in any IMAP mail account folder then you are deleting off the server. If you delete any emails off the server via webmail then when Thunderbird synchronises with the server, it will show you a copy and the emails you deleted off the server will also be deleted off Thunderbird. The folders are one and the same.

if you want to keep a copy on your computer but delete off server, then synchronise the folder to get a copy, then go offline and then move the email into Local folders, which stores email on the computer and is not connected to the IMAP server. Then you can go back online and delete the email in the IMAP account, this will delete the email off the server. If you see emails you have deleted still on the server, then compact the folder. Right click on folder and select 'compact'.

You can set Thunderbird to auto expunge deleted emails off server here: "Tools -> Account Settings -> Server Settings for the IMAP mail account Select: Clean up ("Expunge") Inbox on Exit it will compact the Inbox folder when you exit Thunderbird.

If you check "Empty Trash on Exit" it will also empty and compact the Trash folder when you exit. Click on OK to save changes.

More info on deleting in IMAP mail accounts:

• http://kb.mozillazine.org/Deleting_messages_in_IMAP_accounts

more info on IMAP mail accounts:

• https://support.mozilla.org/en-US/kb/imap-synchronization

Pop mail accounts can only access the server Inbox, those emails are downloaded to Thunderbird profile and are on your computer. by default those messages on the server will be deleted. However, you can choose whether to keep messages on the server or not.

Dear Toad Hall, I want to keep de e-mails on the server. I do not need help to delete the mails. They disappear without help. I want to keep them for download on another machine as explained in the question. Will my provider be able to solve this? Thanks anyway

Fred Knijf

IMAP has no "Keep mail on the server for XX days" because mail MUST be kept on the server it is inherent in the whole IMAP protocol.

If mail is disappearing it is most likely your pop machine not honoring the leave on server setting for some reason (it is not 100% when set to so many days)