Hello there

Strange characters in the outgoing mail . There must be a reason to verify that there are indeed strange characters are appearing in that input field of Thunderbird. Go to account settings then go for the encoding settings that work for the incoming and outgoing email verify them there.

Can you check for firewall settings in the anti virus program that is running on that pc? That might block certain internet connections there for the program try to turn that off and see if something changes ?

Strange symbols in the outgoing mail are often caused by text encoding settings or errors. If there are strange symbols in the edit field of Thunderbird. Then see if changing font type is solving something that might and could solve this. Go to tools then options then display then fonts and colors then go to Advanced. Try to change the default fonts to see if it resolves that issue some how.

Questions are open

Greetings googlethunderbird.

The -- at the beginning indicates a signature is attached, but the garbled display is due to an incorrect format. Account Settings, select the account in the left pane, then look at the signature settings. Only txt, html and picture formats are allowed.

Hello there

Yes you can find something in that signature field there hence , try to erase that later. Try to screenshot that something that is there and what to find there in that signature column , and send it to us before erasing it if that is a possibility to do? It might be that there is some sort of scrambled text to . https://support.mozilla.org/en-US/kb/how-to-make-screenshots