Case 1: After switching the ISP from Comcast to AT&T, the client can’t send
email.
Resolution: In the fight against spam, more and more Internet service
providers require their subscribers to send mail through the ISP's own SMTP
servers. You will need to setup AT&T SMTP server to send email out. This how
to may help: How to
setup Outlook Express using ISP SMTP Server
Case 2: There are two computers in a Small office. One computer can send and
receive email. Another one can receive email only and no send email. There
is not hardware, software and ISP changed.
Resolution: After comparing both computers’ settings, we found the working
computer is setup to use ISP SMTP server to send email. The problematic
computer was using other email ISP SMTP. Changing the settings using the ISP
SMTP server fixes the problem.
Case 3: When sending email, the user receives this message: The connection
to the server has failed. Account: 'pop.mail.gmail.com', Server:
'smtp.mail.yahoo.com', Protocol: SMTP, Port: 25, Secure(SSL): No, Socket
Error: 10060, Error Number: 0x800CCC0E.
Case 4: If you have Norton AntiVirus enabled on your
computer, you may have to make configuration adjustments to use Outlook or
Outlook Express.