Wednesday, January 05, 2005

Further Reducing Spam with Sender Filters

While I only get a measly 30-40 spam messages a day, Bill Gates receives 4-million peices of spam a day. Spam is a big problem. It slows the internet down, spreads viruses and worms. Arriving back from holiday, I have had the joy of searching through the 300 spam messages in my IMF archive folder.

As you know from my Layers of Spam blog post, I have the IMF enabled, and configured, I have it cranked up pretty high, but you know what spam gets through? Spam from my very own domain, Spam from myself to myself. How horrible is that?

Well, with thanks to Terrell, I came across yet another layer of spam protection.

Sender Filtering
Sender filtering looks at the senders domain, and rejects it based if it appears in the list. Adding your own domain to this filter can reject mail from the Internet sent from your domain (since that should all come from internal sources ... right?)

Here's how I did it:

  1. Open Server Management and expand Advanced Management, First Organization (Exchange), Global Settings and right click on Message Delivery and choose Properties.

  2. On the Sender Filtering tab, add your domain in the format of and click OK.

  3. Then check the box Drop connection if address matches filter. I also decided to check Filter messages with blank sender since a lot of spam seems to come through with blank from addresses also

  4. Now the filter is created, we need to enable it. Back in First Organization Group (Exchange), expand Servers, {ServerName}, Protocols, SMTP and right click on Default SMTP Virtual Server and choose Properties.

  5. On the General tab, click the Advanced button

  6. Select (All Unassigned) and choose Edit.

  7. Ensure Apply Sender Filter is selected to enable the filter configured above. The others will be checked if you already followed my Layers of Spam blog post. Click OK until you're back at Server Management.

Now you're done. The filtering is enabled, and you'll stop getting spam from your own domain!

Let's just hope Bill Gates is spot on with his prediction. I could do without spam all together.