I have a private and a business email address (in the same Thunderbird profile). When sending an email to someone I know in both worlds (who also has a private and a business email address), it can easily happen to send from or send to the wrong address.
I would like to have a Thunderbird add-on that allows me to specify¹ a whitelist² per contact which lists the sending address(es) I may use.
If trying to send from a non-whitelisted address, it should warn me (instead of correcting it automatically).
It should not require me to specify a whitelist for all contacts.
¹ I want to specify the whitelists manually. Example: for my contact firstname.lastname@example.org, I add "email@example.com" to the whitelist. Now when I try to send an email to firstname.lastname@example.org, I can only do so if I select email@example.com as sender address.
² While a blacklist would work in the case of only two accounts, too, I actually have many more accounts, so it should be a whitelist.