Keyword Filter for forwarded emails


I have problems applying filters to emails forwarded from an external server (such as Gmail).

Let’s say I have 2 “forward-only” emails set up in DreamHost: -> ->

I can successfully apply filters on these, so that any emails coming in through "" will go to a folder named “A”, and any emails through "" will go to a folder named “B”.

However, I have another “forward-only” email set up: ->

Now, I don’t directly receive emails to this address, but I’ve set it up to catch forwardings from Gmail. So, it’s like this: -> ->

The problem is that I can’t find a way to filter these emails, so that they will be moved to a folder “C”.

I have tried setting up a “To” filter for both "" and "", but to no effect.

Could someone give me some tips on how to set this up?

Thank you.