Avoiding 550 5.7.1 Authentication Required on Outlook 2003
Enthusiast - Level 2

After switching, apparently belatedly, from incoming.verizon.net and outgoing.verizon.net for POP3 email to the new SSL settings ( http://ow.ly/3jpPIF ) on Outlook 2003, I was unable to send email, getting the error " 550 5.7.1 Authentication Required ."

By trial and error, I fixed this by going to "More Settings" in Outlook -> Outgoing Server tab, leaving "My outgoing server (SMTP) requires authentication" checked, and selecting "Use same settings as my incoming mail server." The error occurred when "Log on to incoming mail server before sending email" was selected.