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

[Chuluun]

Don’t know what went wrong with my Vista Mail setup from last 4 days I’m just unable to send any email. There is o problem in receiving the emails, just cannot send any more. Every time I try doing that, here is what I get:

“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.”

I you guys need more info for helping me out, here is what I get in the rejected emails:

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 seehttp://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

Somebody please help me getting rid of this problems.

[Domi.nick]

Well personally I don’t have any idea what could be the cause of the problem and how it can be solved. But as mentioned in your error itself, did you tried referring the URL mentioned (support.frontiernet)? Just check it, hope you will get some info.