can't send emails - but can receive them - have same internet prov

[Heather]

The message could not be sent. The authentication setting might not be
correct for your outgoing e-mail [SMTP] server. For help solving this
problem, go to Help, search for "Troubleshoot Windows Mail", and read the
"I'm having problems sending e-mail" section. If you need help determining
the proper server settings, please contact your e-mail service provider.

The rejected e-mail address was '(e-mail address removed)'. Subject
'Read: Meeting Reminder', Account: 'POP3.frontiernet.net (1)', Server:
'SMTP.frontiernet.net', Protocol: SMTP, Server Response: '554 5.7.1 Error:
The message could not be sent because your e-mail program needs to identify
itself to the sending mail server. Please see
http://support.frontiernet.net/smtp for instructions on how to correct this
setting in your e-mail program.
(74-47-183-81.dsl2.nrwc.ny.frontiernet.net[74.47.183.81] to <Client host>)',
Port: 25, Secure(SSL): No, Server Error: 554, Error Number: 0x800CCC79

 

[Gary VanderMolen]

So did you follow the instructions referenced in that error message?
( http://support.frontiernet.net/smtp )