What do Microsoft and Viagra have in common?

Trouble with spam rings.

eWeek:

"Microsoft Corp. and Pfizer Inc. on Thursday announced parallel lawsuits against two international spam rings pushing a variety of drugs, especially those purporting to be generic versions of Pfizer's Viagra product. The two companies filed a total of 17 lawsuits in courts in New York and Washington state."

'Spam rings'...? New one on me.