Stop Spamming Yourself!

We all knew that the huge decrease in spam that occurred after mccolo.com was shutdown would be short-lived.

Recently, I've a seen large increase in the amount of spam to me apparently coming from me.

Note: Exchange 2003 and 2007 displays the "from" address
of these emails as the full SMTP address (i.e., jeff@expta.com), rather than the resolved name (Jeff Guillet), to show that the email actually came from outside the company.

To stop spamming yourself, configure your SMTP gateway server to reject all external emails from your domain(s). Here's how to do this using the Exchange 2007 Edge Transport server:

1. Open the Exchange Management Console (EMC) on the Exchange Edge Transport server


2. Expand Microsoft Exchange and select Edge Transport


3. Double-click Sender Filtering to open its properties


4. Click the Blocked Senders tab and click Add


5. Select Domain, enter your SMTP domain name, Include all subdomains, and click OK


6. Click OK again to close the Sender Filtering Properties window

Now the Edge server will not accept non-authenticated emails from your domain to your domain. Note that this does not affect any external Windows Mobile or Outlook Express clients from sending email into your domain, as long as these users are authenticated.

You can use the following VB script to test the new settings:

'VBScript to test SMTP email

CONST mailServer = "incoming.mydomain.com"
CONST emailAddress = "user@expta.com"

Set objEmail = CreateObject("CDO.Message")
objEmail.From = emailAddress
objEmail.To = emailAddress
objEmail.Subject = "Test Message"
objEmail.Textbody = "This is a test message."
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") = mailServer
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25
objEmail.Configuration.Fields.Update
objEmail.Send
MsgBox "SMTP Email sent successfully to " & emailAddress, vbInformation, "TestSMTP"

Change the mailServer variable to use your Edge Transport server name and the emailAddress variable to use your internal SMTP address. The script will send SMTP email to the email address from the same email address.

Before Sender Filtering is enabled, the script will return a success message:

After Sender Filtering is enabled, the script will return a Sender Denied message: