Thunderbird: Cannot send email but can read emails [SOLVED]

[Daniel B. Thurman]

Kevin J. Cummings wrote:

Wow.  That was a chore.  It turned out that it was the
exchange server - that I had to allow my local users
the right to relay messages via the Exchange Server.

That was part of the problem.  I also had to fix my
DNS entries so that  my  email server IP address uses
local IP addresses rather than public ip addresses.

Thank you all for responding and giving me the clues
in finding my mistakes.

* This message is sent to by Thunderbird

Dan