Can I set a default reply-to account (Windows 10)

[Jim Thompson]

If I select a photo in the file explorer and do send to email recipient, it randomly selects one of my email accounts to send it from.

Is there a way to stop this?

[tanstaafl]

I can't reproduce that, it always uses the default account (and its main identity). I suggest you try setting a different account as the default account, and then set the desired account as the default (using tools -> account settings -> account actions -> set as default).

If you start Thunderbird in safe mode (help -> restart with add-ons disabled) and then "select a photo in the file explorer and do send to email recipient" it should use the already running instance of Thunderbird (which is in safe mode). Does using safe mode make a difference?

Does it make a difference what type of file you try to send?

What version does help -> troubleshooting information say you are using?

Is this a new problem or did you just not notice it until now?