I have more than one e-mail account. If I open a message from one of them, I get always the default address as sender. It would be useful that senders address will be adapted to the account where I am.
I agree. When replying to an email Thunderbird should use the address in the received email rather than the default identity in settings. I have a number of email addresses that I use for different purposes and I have to constantly change my outgoing email address to the one in the received email. If memory serves, I think Thunderbird used to not default to the primary email address, but maybe I am thinking of another program?