Is port 465 the correct one for yahoo.ca accounts as well? I've had mine set at 993 the entire time I've been using this email address while I've had this internet provider. That is also the same port I have been using for another email address that I use Mac Mail for. It has worked up until today, and I got the same error message for three different emails (550-5.7.1) I can't verify the smtp.mail.yahoo.com thing either. When I'm in Account Information, it says the Outgoing Mail Server (SMTP) is Yahoo, and the box is checked that says Use only this server. When I'm in the Advanced part of the Account settings, the little window for IMAP Path Prefix is blank. And it says Authentication is Password.
... View more