[Enhancement] Password prompt limitations

[Kabouik]

It is all quite minor but:

• The password prompt cannot be interrupted/cancelled with ^C, the terminal stays busy until something is typed and confirmed. This seems a bit unusual and multiple times I had to knowingly type a wrong password just to free my terminal (like if I realized it wouldn't work anyway because of a typo, caps lock, or "unsecure apps" not enabled on the server).
• Maybe some visual hint of typed characters (***********) could help correcting typos, but I think opinions may diverge there, as password prompts with not hints are also quite common in UNIX.
• The account cannot be opened if the IMAP credentials are correct but not the SMTP credentials. I think it would be best if SMTP just limited sending but not cache access and email reception.