Question : HELP - UNABLE TO SEND MAIL!! Small business server 2003 is blocking our pop3 email clients sending mail

Hi,

Since we setup our 2003 SBS and created a new domain, our workstations configured with pop3 accounts are unable to send any outgoing emails outside our domain.

We could send emails externally for 1 day, now all emails being sent outside come back with a system admin undeliverable error message.
When we hit send/receive button the account is checked ok and comes back with no error message.
We are still receiving emails ok.

I'm sure it has something to do with either SBS 2003 exchange server, sql server or maybe DNS?
Usually we use 2000 or 2003, not SBS!!

I have disabled the sql and exchange services on the server. could this interfere with pop3 accounts??

we have checked the broadband line and checked the bt mail servers and we're told all is ok.

looks like an issue with SBS....

any ideas as we have no email!!!!!!!!!!!

thanks in advance!!

Answer : HELP - UNABLE TO SEND MAIL!! Small business server 2003 is blocking our pop3 email clients sending mail

550 relay error usually means you failed authentication to the outgoing mail server.  If your clients are using Outlook, look at the email account settings.  I think under the advanced settings there is a tab that deals with authenticating to the outgoing mail server.  I belive it says 'the outgoing mail server requires authentication'  then you have to enter the users account name and password.