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aldi2 asked on

SMTP error from remote mail server

Hello, we have a customer that we are not able to send email messages to.  No user can send messages to this specific contact, but I can send from home with no problem.  What is the easiest way to find out if the problem is with my mail server or his. Please see message below.

Mail server: Exchange 2003 SP1 on SBS 2003

This message was created automatically by mail delivery software.  Please do not reply to this message.
Do not use the "Resend" option in your mail client, as this will not resend your original message.
If you wish to resend this message, you will have to compose a new message and send it instead.

A message that you sent could not be delivered to all of its recipients.

The following address(es) failed:

    SMTP error from remote mail server after RCPT TO:<recipient@hiscompany.com>:
    host hiscompany.com.s8a1.psmtp.com [xx.xx.x.xx]:
    554 No relaying allowed - psmtp

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Last Comment

8/22/2022 - Mon
Rodney Barnhardt

The best thing is to asked the to whitelist your company in their spam filter. You could also make sure you don't appear on any blacklist: http://www.mxtoolbox.com/blacklists.aspx
Rodney Barnhardt

Since the error is coming from their server, you really need to contact their mail administrator and work with them to determine the problem.

Is your valid IP registered in reverse lookup zone?
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Walt Forbes

rbarnhardt, thanks for replying.  I checked and got the results below.  I know that my mail server is not relaying spam, since it has rely restrictions on.
Is it black listed in some of them because it sees the ip address as dynamic?
It's blacklisted on 10 of them, should I worry about it?

Note that I omitted the whole list to save space

We notice you are on a blacklist. Click here for some suggestions.
 Checking against 124 known blacklists...
Listed: 10 time(s)
 Blacklist Name   Status Reason TTL Response Time (ms)
SORBS-BLOCK  LISTED Dynamic IP Addresses See: Detail
Return codes were: 3599 562
SORBS-DUHL  LISTED Dynamic IP Addresses See: Detail
Return codes were: 3599 547
SORBS-HTTP  LISTED Dynamic IP Addresses See: Detail
Return codes were: 3599 531
SORBS-MISC  LISTED Return codes were: 3599 0
SORBS-SMTP  LISTED Return codes were: 3599 0
SORBS-SOCKS  LISTED Return codes were: 3599 0
SORBS-SPAM  LISTED Return codes were: 3599 0
SORBS-WEB  LISTED Return codes were: 3599 0
SORBS-ZOMBIE  LISTED Return codes were: 3599 0
TQMCUBE  LISTED Return codes were: 7200 0
AHBL  OK   0 47
CASA-CBL  OK   0 47
CASA-CBL+  OK   0 62
CASA-CDL  OK   0 62
CBL  OK   0 16

Amirchoupani, yes. the ip is registered in reverse lookup zone
Rodney Barnhardt

The problem with a dynamic IP is that you could have gotten one that was previously being used for spam. A number of them mentions "see details", was that a clickable link? If so, did you click it?
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rbarnhardt, I want to mention that my IP is static, it never changes; I have the same for about two years.

Here are the details of the link on one of the black list database.

Dynamic IP Space (LAN, Cable, DSL & Dial Ups)  
Netblock: (
Record Created: Sun May 14 11:11:09 2006 GMT
Record Updated: Sun May 14 11:11:09 2006 GMT
Additional Information: [MU] Dynamic/Generic IP/rDNS address, use your ISPs mail server or get rDNS set to indicate static assignment.
Currently active and flagged to be published in DNS
If you wish to request a delisting please do so through the Support System.
Rodney Barnhardt

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Thanks for your help!