I have enabled Anti-spam on my internal transport server,

I have content filtering enabled and have blocked the word viagra.

I can still send emails into the Org with that word in the body and subject of an email,

In the Agent Log there is nothing

I have restarted the transport server and the servi

Hello,

Firstly, I recommend you check the headers of the headers of one of the spam emails via outlook.

Here is the article for your reference.

View the Internet header information for an email message

http://office.microsoft.com/en-us/outlook-help/view-the-internet-header-information-for-an-email-message-HA101836448.aspx

Secondly, I recommend you use the Get-ContentFilterPhrase cmdlet to view one or all custom words that the Content Filter agent processes.