This is firefox for android community support. For feature requests and bug reports for Thunderbird, you should refer to the appropriate sites. For community support for Thunderbird, see https://support.mozilla.org/en-US/questions/thunderbird

Unfortunately i do not currently have a computer on which to check for such settings, but it would usually be in the download behavior section referring to leaving, or not, emails on server when they have been downloaded by that email client. Someone in the Thunderbird forum may know where that setting went to hide if it still exists but you cannot find it. (I will yet try to check in a day or so when i can. Best wishes.)

Hi James, It sounds like you had your accounts set up as POP3 account type, instead of IMAP. You'll need to set it to remove messages from the server.

1. Go to Tools > Account Settings > [account name] > Server Settings.
2. Uncheck Leave messages on server.

For more information, see Configuration Options for Accounts.

If you're going to access the same account from more than one computer/device, I recommend you switch to using the IMAP account type. For more information, see Switch from POP to IMAP account.

There's a great explanation in the following video:

Thanks for the suggestions, but it didn't help. Went to Tools > Account Settings > (account name) > Server Settings, but there is not now a Leave messages on server. That's what went away?

Hi James, "Leave messages on server" only appears for POP accounts. We'll need some more info about your Thunderbird setup. Could you please do the following:

1. Go to [=] > Help > Troubleshooting Information then click Copy text to Clipboard.
2. Go to https://pastebin.com and go to Edit > Paste to paste the info from your Troubleshooting Information page.
3. In Firefox, click on the three dots to the right of the address, and select Copy Link.
4. Open a reply to this post, and go to Edit > Paste to paste the link to your troubleshooting information.