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  Asked: Mar 14 2008   8:35 PM GMT
  Asked by: Wwebsus

URGENT E-Mail issue 550 5.7.1 Requested action not taken: message refused


Exchange 2003, 550 5.7.1, Exchange error messages

About a couple weeks ago we were forced to change our IP address. Everything changed just fine and we were able to send e-mails without any problems until today we started receiving these messages -- but only from certain domains.

550 5.7.1 Requested action not taken: message refused

Reason: Delivery not authorized
The sender is not authorized to send to the destination.
This can be the result of per-host or per-recipient filtering.

This can't be a filtering problem and I looked up all our DNS information on CheckDNS.com and nothing comes up in error. The MX record looks fine. I can't think for the life of me what I'm missing.

I only have this weekend to resolve it. Help would be MUCH appreciated!

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Last Answered: Apr 27 2008  5:25 AM GMT  by LVK


Latest Contributors: Bdinerman, Buddyfarr, Mrdenny


Sounds like the email admin at the other end has blocked you from sending emails to them.

What domains are the bounce backs coming from?

Use other DNS testing sites in addition to CheckDNS. For example, try dnsstuff.com. If results still come back negative, then it's possible that your messages are being rejected not because of a real-time black list, but because your IP address or subnet is explicitly defined on the list of blocked addresses on the recipient's server.


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Did you relay via other server (SMTP and mai box are not the same server)? If you did not send mail direct from your mail server, you may get that error. That is what we called "Challenge Response".
The Challenge Response system requires senders from external domains to authorize their email address for future communication with your mail server. External senders will only be challenged once.
When the receiver's server get your mail (user@yourdomain.com), it will send another mail to your SMTP server to check if that email (user@yourdomain.com) is valid. If user@yourdomain.com is not on that SMTP server, the receiver will reject your mail and your will get 550 5.7.1 Requested action not taken: message refused.

LVK
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Wwebsus  |   Mar 14 2008  8:55PM GMT

The two domains are pscinfogroup.com and bellsouth.net

I thought that it was something on their end when I first received a bounceback. But I’ve got 3 different users getting NDR from these domains. The other NDR says:

Reason: Bad sender’s system address
The sender’s system specified in the address does not exist or is incapable of accepting return mail.
This means the address portion to the right of the @ is invalid.

but goes on to say

<Our IP address> is blocked by ldap:ou=rblmx,dc=bellsouth,dc=net 550 Mail from this IP address is not allowed. Your computer has been identified as a compromised machine which needs to be cleaned in order to send email to Bellsouth. Please run an updated anti-virus/anti-spyware program on your machine immediately. If you believe this message is in error, please contact BrightMail at <a href="mailto:zbl-fp@review.symantec.com">zbl-fp@review.symantec.com</a>

Thank you for your quick response!

 

Mrdenny  |   Mar 14 2008  11:57PM GMT

Have you contacted Brightmail? Sounds like the person who used to use the IP which your mail server is now on was flagged as a spammer, and now you are paying for it. If you contact them and let them know that you just got the IPs from your provider they should remove the listing.

 

Wwebsus  |   Mar 15 2008  5:31AM GMT

Yeah I think that will be my best bet. I think at least they can tell me why we were blocked if not for the reason you stated. Its just strange because it popped up out of the blue — we could e-mail them fine yesterday. Thanks for the responses.

 

Wwebsus  |   Mar 20 2008  6:49PM GMT

I’ve been doing more research and we’ve been added to a few more domains block lists, including a hotmail address. Now we’re getting a message

554 Transaction Failed Spam Message not queued.

I’ve run a few DNS reports and checked for reverse DNS. I’ve even checked e-mails going out from us and we’re not sending out any spam through our server. There must be some technicality that they’re blocking us on that I can’t figure out.