Can't send mail in Outlook 2007

[Zach]

I have been successfully using outlook 07 for a while now, but recently it
stopped sending mail.
I can still receive mail from the server, but every time i try to send
anything i get an error saying:

Task '(e-mail address removed) - Sending' reported error (0x800CCC78) : 'Cannot send the
message. Verify the e-mail address in your account properties. The server
responded: 550 This domain is blacklisted, consult your postmaster'

Can this be fixed by me, or will i need to talk with my 'postmaster'
mentioned above?

 

[K. Orland]

It would appear the domain you're sending from has been blacklisted, usually
because of suspected spamming. However when I check dnsstuff.org and used a
few other lookup tools, I don't see your domain on any blacklists.
You should double-check your email address in your account properties and
authentication as well to both your POP3 & SMTP servers. Also, very your SMTP
outgoing port. What's recommended by your ISP should be on their website
where it details how to set your account up. The default is port 25 but this
is now often blocked by ISPs because many spammers have used it in the past.
I think often 587 is the one that's used instead but as I said, check your
ISP website.