I noticed something today about attachments.

Spam Filter has the option to blacklist attachments, you could put in something like this:

*.zip
*.exe
*.bat

Now, you might think you have protected your users from any attachments with these three attachment types right?

Well, not so fast.  The attachment blacklist only applies if the message size is under the value set in MaxMsgSizeForSpamFiltering.

If you have a block on .doc, and someone send a .doc file that is 5 megs in size you will end up getting something like this:

X-SF-WhiteListedReason: Whitelisted - Email size exceeded MaxMsgSizeForSpamFiltering

Is this by design or a bug? 

Thanks for the update regarding the filter list, a bit unfortunate since the ability to block attachments is not really 'real'.

I would like to suggest another item to be made sticky (or perhaps part of the same sticky thread).  The item that I think is of interest to people is the current minimum network reliability value being used for SFDB and SFDC.  I think the default value for SpamFilter is 3, but I read in the past that the minimum value has changed over time and it is now much higher.

Someone trying to make adjustments to the sensitivity of the network reliability, might increase it to 6  or 9 etc. but it would actually not be doing anything because they are not above the minimum value used by the SFDB/SFDC.