Spammed By Own Domain

[svenmontgomery]

Hi all,

I seem to be getting alot of spam from fake email addresses with my domain name ie dqkd@domain.com.

Anyone know how I can ensure only authenticated Active Directory users addresses are accepted on incoming mail.

I have had a look at using reverse DNS but find some smaller companies and even ourselves haven't got this setup.

Hoping theres is a tick box I have missed.

thanks in advance!

 

[zbnet]

Start with this and see if it makes any difference:

http://support.microsoft.com/kb/823866

 

[KRPGroup]

We had the same problem and we had to use our smtp gateway (Trend IMSS) server to create approved list of recipients as the server was being hit so hard it had a queue 6000 msg and growing.

 

[zbnet]

Yes, that is also a good idea if you are being hit with many many spam messages.

 

[svenmontgomery]

Its not so much the volume but the fact that it looks like its coming from our domain. The organisation executives do not comprehend mail spoofing etc. They just want it stopped.

I had a look at the MSKB article and have checked that I have marked 'Filter users not in the directory' but it either doesn't work correctly or doesn't do what I thought it does. (Maybe clarification if im reading wrong)

We have too many account changes to start messing about with white lists for known accounts.

Frustrating that such a simple method can pass this spam through.

 

[Zelandakh]

You need an SPF record on your own domain name. Then in your anti spam software you set it to delete emails that fail SPF.

This problem goes away completely if you do those two little items.

 

[58sniper]

Make sure that if you enable the recipient filtering that you also enable tarpitting to reduce the traffic.

Pat Richard, MCSE MCSA:Messaging CNA
Microsoft Exchange MVP