As of yesterday, suddenly cannot send mail, although am still receiving mail.
Mac OS 10.11.6; Apple Mail 9.3.
Coincidentally -- or not? -- can no longer receive or send email from my iPhone when wifi is enabled.
Solved! Go to Solution.
There's a partial explanation at this link.
Port 1025 became the one Telus now uses for all SMTP traffic whether from within it's network or outside. Previously users would be able to send mail when connected to legacy ports only when connected to a point on the Telus network. For instance, sending mail from my laptop at my brother's place (Shaw) would not work, but if I connected to a friend's (Telus) Wi-Fi network - all the pent-up emails sent. The use of port 1025 with SSL has fixed this issue at least for the most part!