[chrisBob]

I have had a similar experience. I just moved from my alumni organization's pop mail to iCloud for my personal email. I immediately started getting a ton of spam, and even contacted apple support about it. I am not sure exactly what the issue is, but the spam messages are all forwarded from my alias @stockbridges.org and iCloud doesn't filter them at all as far as I can tell.

Most of my reason for moving was that I also just purchased an iPhone, and the integration seems much better. Apple's mail program on the mac had a lot of trouble with gmail. I actually contacted apple support about the spam (free since I just got a new phone), and they just told me to mark it and forward it to [e-mail] which doesn't seem to help. I think my next step will be to submit a bug report. I love apple, and my new iPhone5s, but the spam is a hassle.