[pm7]

I recommend checking out add-on Virtual Identity for Thunderbird. It will use "To" address as "From" by default when writing reply, allows editing "From" directly in new mails and will remember what address to use with any recipient and.

Unfortunately, some mail providers (like Migadu.com) block sending mails with "From" anything other than primary user address, even through they "support" catch-all. I was especially disappointed as that stopped me from using IDN mail address. I successfully created mail account using Punycode and I was able to receive mails with national characters, but their filter stopped me from sending.

I know IDN mail address is risky, but it's something I wanted to test. My surname contains non-ASCII character.

They indicated in January that they are working on allowing customization "From" filter customization, but it is still now available and contact with them is very difficult (they are not replying to mails unless you repeat question a couple of times). To be fair, I'm not paying yet (I wanted to test IDN works and it did not, so I'm not very interested in paying when they offer free account anyway).