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How can I prevent invalid e-mails bearing my domain name?

Posted on 2008-11-03
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Last Modified: 2012-05-05
e-mails are currently going around, with an e-mail address that bears my domain name. How can I prevent this? I have checked and there is no such e-mail address on my exchange server 2003. I have a sonicwall firewall NSA 3500.
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Question by:bobox00
6 Comments
 
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by:chilternPC
chilternPC earned 100 total points
ID: 22868399
someone has hijacked your email name - its very easy to set up an email with a fake (or someone elses) email address as the return address, this enables spammers to flood the market and the return addresses get the flak
to stop emails being recieved for unknown users:
on your exchange you can configure the catch all email to simply reject unknown email addresses.
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war1 earned 200 total points
ID: 22868458
Hello bobox00,

Make sure your computer is not an open relay
http://www.postcastserver.com/help/Blocking_Open_Relays.aspx
and
http://support.microsoft.com/kb/324059

If you have control of the server, you can Integrate SPF and DomainKeys, which would help to stop spoofing in the future:

SPF:
http://www.openspf.org/

DomainKeys:
http://domainkeys.sourceforge.net/

Hope this helps!
war1
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Author Comment

by:bobox00
ID: 22869052
Will a security certificate help prevent people from using my domain name to send e-mails illegitimately?
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LVL 27

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by:Tolomir
Tolomir earned 100 total points
ID: 22870710
Well the problem with emails is everyone can run a mailer sending spam with any email address.

All you can make sure, as war1 points out is that receiving email servers drop all emails with your sitename that is not SPF signed: http://www.openspf.org/FAQ/What_is_SPF

Still any mailer not using SPF will receive your emails and send them to the associated receivers.

Of cause antispam measures can be still intact.

Tolomir
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LVL 1

Assisted Solution

by:maximaal
maximaal earned 100 total points
ID: 22894750
We had the same problem.
We installed GFI Mailessentials and followed:
http://forums.gfi.com/Spoofed_SPAM_from_MIME_FROM_addresses_that_SPF-FAIL/m_900759763/tm.htm

problem solved.
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Author Closing Comment

by:bobox00
ID: 31512751
Thanks guys.
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