PLEASE HELP: Outlook2003 Send Mail Error

[Van]

Can anyone help me with this problem. Everytime I try to send out an email.
It gets rejected and I get this message:

The following recipient(s) could not be reached:

'(e-mail address removed)' on 5/5/2010 4:26 PM
554 5.2.1 554 AOL will not accept delivery of this message

 

[VanguardLH]

Can anyone help me with this problem. Everytime I try to send out an email.
It gets rejected and I get this message:

The following recipient(s) could not be reached:

'(e-mail address removed)' on 5/5/2010 4:26 PM
554 5.2.1 554 AOL will not accept delivery of this message

Possibilities:

AOL is your sending mail server but you didn't configure the e-mail account
that you defined in Outlook to authenticate to their SMTP mail host.

AOL is the recipient's domain (not yours) and your sending mail server is on
their blacklist, or your sending mail server doesn't have a reverse DNS
lookup (A record) for its IP address in its DNS server so AOL can validate
the host that is connecting to the AOL mail server. In either case, you'll
have to contact your e-mail provider to tell them that AOL won't accept
e-mails from their domain.