Are you receiving bounced email which almost similar to below?

******* Begin of Bounced Email Sample *******

From:  Mail Delivery System <Mailer-Daemon@yourdomainname>

Subject: Mail delivery failed: returning message to sender 

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

example at example dot com

    SMTP error from remote mail server after initial connection:
    host mail.example.com [0.0.0.0]: 554 Service unavailable;

    Client host [Your Email Server Name] blocked by sbl-xbl.spamhaus.org;
    http://www.spamhaus.org

<Follow by your original email to example at example dot com> 

******* End of Bounced Email Sample *******

WHAT'S THIS? 

If your emails are unable to reach certain recipients OR some one is unable to reach you, your email server may be listed under the SPAM databases.

SCENARIO? 

A couple of days ago, one of my clients, Mr. A reported that his customers are experiencing the below:

i) Receiving Mr. A's email(s) with the word "SPAM" on the front or back of the original subject

ii) Unable to reach Mr. A as Mr. A's email server is rated as SPAMMER in SPAM databases

ANY REFERENCE?

i obtained this report from URL mentioned below. 

Source: http://www.spamhaus.org

Ref: SBL63731

202.75.32.0/19 is listed on the Spamhaus Block List (SBL)

13-Mar-2008 21:32 GMT | SR02

spam source range

2008-03-13 21:30 GMT -- TM.NET.MY has contacted Spamhaus. Now we're waiting for them to remove the spammers.

2008-03-13 04:47 GMT -- TM.NET.MY customers: Please ask tm.net.my or your ISP or hosting company to resolve this issue. Spamhaus cannot assist you and we cannot remove individual IP addresses in this range. 202.75.32.0/19 has a very serious spam problem and it must be fixed by tm.net.my before we can remove the listing. Spamhaus attempted to contact TMNET including addresses which tm.net.my gave to Spamhaus specifically as point-of-contact for SBL listings, and also at other addresses at @tm.net.my, @exabytes.com, @netmyne.com, @celcom.com.my, and @tmnet.com.my. We will remove this listing after TM.NET.MY (or its appropriate hosting company) has removed the spammers and lets us know. That could happen very quickly (hours) if TM.NET.MY takes swift action against spammers, but so far Spamhaus has not received word from TM.NET.MY that they are taking any action.

202.75.32.0/19 equals the range 202.75.32.0 to 202.75.63.255, inclusive.

CAUSED BY?

End users who do not comply cyber law

IMPACT?

We may not able to send/receive certain email addresses for the time being.

It may be permanent if SPAM is ongoing. 

RESOLUTION?

Users are encourage to co-operate to resolve this matter.

PREVENTIVE STEPS

1) Never, ever reply to a spam message

2) Don’t click any links in a spam email

3) Don’t forward an email from someone you don’t know to a list of people

4) Publish your email address on website

5) Don’t use your home or business email address as primary contact when registering stranger website

6) Before you join a list, make sure the list owner or Web master will not sell your address

7) Preview your messages before you open them

8) Use a complicated email username

9) Use a spam filter

10) If your organization has an IT department, forward any spam that gets through to it

11) Make sure your privacy settings are set so you don't receive marketing from other sites in your AOL and Yahoo profiles

12) Never use your email address as your screen name in chat rooms