Outlook recieves, but will not send mail

[Guest]

Email worked fine yesterday, suddenly stopped sending mail today. I am
running Outlook 2003 on Windows XP. When I send a message I get the
following message bounced back immediatly: 503 Valid RCPT TO <recipient>
must precede DATA
It's not my server's problem since my webmail function with them (Earthlink)
works fine for both sending and recieving. I have changed NOTHING in the
past few days and have no idea if a new SP installed recently. I tried
adding Outlook to my firewall list, but only Outlook Express is listed under
the add programs options. I have checked all the STMP/POP info and all seems
correct. Help!!

 

[Vanguard]

Email worked fine yesterday, suddenly stopped sending mail today. I
am
running Outlook 2003 on Windows XP. When I send a message I get the
following message bounced back immediatly: 503 Valid RCPT TO
<recipient>
must precede DATA
It's not my server's problem since my webmail function with them
(Earthlink)
works fine for both sending and recieving. I have changed NOTHING in
the
past few days and have no idea if a new SP installed recently. I
tried
adding Outlook to my firewall list, but only Outlook Express is listed
under
the add programs options. I have checked all the STMP/POP info and all
seems
correct. Help!!

Did you configure your e-mail account to authenticate to their SMTP
server?

Did you check the spelling of the recipient's e-mail address to make
sure the domain was correct and that there were no leading of trailing
spaces?