I'm using cPFence on 7 of my main servers, for a few weeks now.
I have to say I'm very pleased with it. No problems at all.
On one email server I have around 300GB of emails, and it continues to find emails "here and there" with malware, and moving them to quarentine.
I'm not sure if all of those are real "bad" emails, because I haven't check them all, but the ones I did I was glad they were quarantined. Most important is absolutely no complains from customers.
I have a personal (of mine) email account that I use to register everywhere for non important things, and that account receives lots of SPAM. For that account only, a few days ago, it detected 2400 infected emails! WOW.
I actually like the fact that cPFence doesn't have a GUI/dashboard.
But, in this case, when lots of emails are quarantined, it would be handy.
I opted for the auto-quarantine feature, and I feel comfortable with it.
This is just my small (and humble) review.
Cheers,
Luis