I have had hosting accounts with a few providers in the past based locally and overseas, I am not going to name names. Typically I would have bought their basic linux hosting packages which (through their web based cpl's) allowed me to setup emails @respectivedomainnames.com. In every case I found even within a matter of hours the site owners would receive crazy amounts of SPAM in their inbox.

Some hosting companies charge quite a lot IMO for applying spam filters, while I read that the likes of Blacknight include this service for free on their shared linux hosting plans. Is this true? and if so, does it work?

I have a number of websites coming up that need hosting and spam free email hosting also @theirdomainname.com. The domain names are already registered elsewhere, but the hosting still needs to be purchased.

Where would you recommend I go. My hosting requirements would be a LAMP config (>= PHP5) , with decent space and monthly transfers.

But the spam free email is absolutely critical.