can't send mail to only some servers 550 error. please help!

I'm able to send and recieve, but only to some servers - all the same servers. two servers that I can not send to are cyberus.ca and aol.com.

I've put together a bunch of technical details for you guru's. Here are my details.

First the error I have recieved on each message sent to Cyberus .ca from my email server Concept4.ca returns this:

From: mailer-daemon@concept4.ca <mailer-daemon at concept4.ca>Add to Addressbook
To: <user@concept4.ca>
CC:
Subject: Mail delivery problems
Date: Wed, 7 Apr 2004 21:54:47 -0400

SMTP error occurred while sending message to following recipient(s)
webmaster@cyberus.ca
550 Sender verify failed

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This is a screenshot of my MX at everydns.net - see www.eappearance.com/everydns.jpg

You'll notice that i have two A names pointing to my web server and then i have mail.concept4.ca and the MX set to another host on another IP.

Please see the reported readings from dnsreport

http://www.dnsreport.com/tools/dnsr...ain=concept4.ca

I'm quite sure that the MX settings are ok but who knows maybe i'm missing something here.

Thanks.

I'm still having problems. it turns out that the end server who is trying to recieve my mail is rejecting it because it can not be verified.

I've put together a bunch of images of my DNS entries, my server logs of two accounts on the same server. NOTE: one domain is working on the server while the primary one is not.

please go to www.eappearance.com for the logs. they're posted right up there.

thanks.

ISSUE HAS BEEN SOLVED!!! see this posting at

http://www.webhostingtalk.com/showt...091#post2002091

argh.. turns out that solution works, HOWEVER it is incorrect.. please see http://www.rscott.org/dns/mx.html

does anyone else have any input on this?

yap thanks anyways all.. please go to this forum for updates on this issue..

http://www.webhostingtalk.com/showt...091#post2002091