Email filtering using regex

Hello all,

I am receiving a considerable amount of spam lately, although I have SpamAssassin on and a lengthy list of manual filters in place. The new type of spam does not have a wording pattern that I can use to create a filter; on the other hand, it contains max 2 lines of sensible text and a link. Here's a real-life example:

or

I suppose what I need is a script (regex?) filtering off all messages that are shorter than XX characters and contain a link. Any help to that direction would be highly appreciated.

Thanks,

Alex