[IMail Forum] error 550

[Chester Alan Godsy]

We have a small business.  We are currently on a Covad network using DSL.  Our server runs windows 2000 Pro with all the services packs installed for Windows and I-Mail.  This server also runs Apache and Tomcat.  We just ran a virus scan to make sure the server was clean of viruses, which it is.

We have been sending mail using imail SMTP via Outlook and Eudora and the Web Mail Interface with complete success,
but just recently we are having intermittent trouble sending mail. 

Sending to certain email domains always works i.e. sending to this domain works.
And sending to some email domains does not work i.e. earthlink.com (intermittent mostly fails), and planetkc.com

Here is a copy of the log for one of the failures:

==================================================================
Here is a sample from the log of a failure where I sent mail from [EMAIL PROTECTED] to [EMAIL PROTECTED]
Some times this same test will work, and most of the time it fails.

1st example sending from [EMAIL PROTECTED] to [EMAIL PROTECTED]

09:08 16:31 SMTP-(0000012C) Trying earthlink.net (0)
09:08 16:32 SMTP-(00000120) Connect earthlink.net [207.217.121.217:25] (2)
09:08 16:32 SMTP-(00000120) 220-snipe.mail.pas.earthlink.net ESMTP Exim 3.33 #1 Mon, 08 Sep 2003 14:30:21 -0700
09:08 16:32 SMTP-(00000120) 220-NO UCE.  EarthLink does not authorize the use of its computers or network
09:08 16:32 SMTP-(00000120) 220 equipment to deliver, accept, transmit, or distribute unsolicited e-mail.
09:08 16:32 SMTP-(00000120) >EHLO mail.us-automation.com
09:08 16:32 SMTP-(00000120) 250-snipe.mail.pas.earthlink.net Hello h-67-100-163-220.chcgilgm.covad.net [67.100.163.220]
09:08 16:32 SMTP-(00000120) 250-SIZE 10485760
09:08 16:32 SMTP-(00000120) 250-PIPELINING
09:08 16:32 SMTP-(00000120) 250 HELP
09:08 16:32 SMTP-(00000120) >MAIL FROM:<[EMAIL PROTECTED]>
09:08 16:32 SMTP-(00000120) 250 <[EMAIL PROTECTED]> is syntactically correct
09:08 16:32 SMTP-(00000120) >RCPT To:<[EMAIL PROTECTED]>
09:08 16:32 SMTP-(00000120) 550-EarthLink does not recognize your computer (67.100.163.220) as connecting from an EarthLink connection.  If this is in error, please contact technical support.
09:08 16:32 SMTP-(00000120) 550 relaying to <[EMAIL PROTECTED]> prohibited by administrator
09:08 16:32 SMTP-(00000120) >QUIT
09:08 16:32 SMTP-(00000120) 221 snipe.mail.pas.earthlink.net closing connection
09:08 16:32 SMTP-(00000120) Creating message from Postmaster
09:08 16:32 SMTP-(00000120) finished C:\IMail\spool\Qf52b001e016c3df0.SMD status=2

==================================================================
2nd example sending from [EMAIL PROTECTED] to [EMAIL PROTECTED]

09:09 10:14 SMTP-(00000784) Connect planetkc.com [208.188.193.247:25] (2)
09:09 10:14 SMTP-(00000784) 220 members.planetcorp.com Microsoft ESMTP MAIL Service, Version: 5.0.2195.6713 ready at  Tue, 9 Sep 2003 10:12:18 -0500
09:09 10:14 SMTP-(00000784) >EHLO mail.us-automation.com
09:09 10:14 SMTP-(00000784) 250-members.planetcorp.com Hello [67.100.163.220]
09:09 10:14 SMTP-(00000784) 250-AUTH GSSAPI NTLM LOGIN
09:09 10:14 SMTP-(00000784) 250-AUTH=LOGIN
09:09 10:14 SMTP-(00000784) 250-TURN
09:09 10:14 SMTP-(00000784) 250-ATRN
09:09 10:14 SMTP-(00000784) 250-SIZE 2097152
09:09 10:14 SMTP-(00000784) 250-ETRN
09:09 10:14 SMTP-(00000784) 250-PIPELINING
09:09 10:14 SMTP-(00000784) 250-DSN
09:09 10:14 SMTP-(00000784) 250-ENHANCEDSTATUSCODES
09:09 10:14 SMTP-(00000784) 250-8bitmime
09:09 10:14 SMTP-(00000784) 250-BINARYMIME
09:09 10:14 SMTP-(00000784) 250-CHUNKING
09:09 10:14 SMTP-(00000784) 250-VRFY
09:09 10:14 SMTP-(00000784) 250 OK
09:09 10:14 SMTP-(00000784) >MAIL FROM:<[EMAIL PROTECTED]>
09:09 10:14 SMTP-(00000784) 250 2.1.0 [EMAIL PROTECTED] OK
09:09 10:14 SMTP-(00000784) >RCPT To:<[EMAIL PROTECTED]>
09:09 10:14 SMTP-(00000784) 550 5.7.1 Unable to relay for [EMAIL PROTECTED]
09:09 10:14 SMTP-(00000784) >QUIT
09:09 10:14 SMTP-(00000784) 221 2.0.0 members.planetcorp.com Service closing transmission channel
09:09 10:14 SMTP-(00000784) Creating message from Postmaster
09:09 10:14 SMTP-(00000784) finished C:\IMail\spool\Qee1102c501788235.SMD status=2

Any ideas on what is going on here?

Thanks for the help.
Chester