Many thanks!  I am, frankly, not best pleased with the web-based displays of Yahoo, and was astonished to discover that AT&T relied on Yahoo for its email.

 As I own a domain, I can add a mail server to it its server at a nominal additional cost and use that as for the email transactions I have run from my former ISP and kept out of gmail and .  Then wave 'goodbye' to AT&T's email.  Then I can stick with Pegasus, which I have used for over 15 years.

Have just switched to AT&T as my ISP, and they run email <name@att.net> through Yahoo.  I have tried to configure Pegasus with imap and pop3., and have had less-than-wonderful results (lots of timeout) and sending seems to default to pop3, rather than imap.  Clues, please?

Thanks in advance ...

Gene Rankin 

IMAP is a protocol that provides access from your email client to mail hosted on an external server like Yahoo, ATT, Gmail, ...

POP3 retrieves email to your email client from an external server

SMTP sends mail from your email client using an SMTP server.

That said, POP3 would not be attemping to send messages, it would be SMTP doing that.  As far as POP3 or IMAP, you'll need to decide which one you want to use.

You might find this site helpful: https://help.yahoo.com/kb/SLN4724.html

As far as troubleshooting goes, you can determine what is going on during any of these transactions by reviewing the associated internet session log.  These logs are created whenever internet session logging is enabled.  That setting is in Tools > Internet Options, at the bottom of the General tab.  I strongly suggest reading the associated help information. 

Be aware that login credentials are recorded in the logs in a format that is easily decoded.  Don't post a log without removing that content.  Don't forget to turn the logging off once you are done troubleshooting.

Also, make sure you are running the newest version Pegasus Mail (v4.72).