Yes, that is correct @yerch82, and the whole point I have tried to make in this thread.
As you say, a possible solution is to change the sender’s details in the account setting to the address you want to be default, rather than the ones used to login to the account.
- You set an account as default.
- Then you change the sender’s details to what you want to be default.
- They don’t have to be the same as the details used to login to the server.
Some servers will not let you login with credentials (3) different to the address you want to send from (2). Some will, but the sent message will include the Sent-from: header which will be the login address (3).