You can't have an email conference without discussing the scourge of our industry, spam, and the Email Insider Summit was no exception. The topic came up a few different times. Here are some of the notes I took:

• Procter & Gamble found that 80 percent of its recipients who hit the "spam" button did not recall ever having done so.

• Cisco found that the biggest reason its BtoB customers clicked the spam button was because their roles had changed and the messages they had signed up for were no longer relevant.

• Habeas tracks 200 million email-sending IP addresses across the world. It estimates that 99.95 percent of those are sending spam. That means that the good guys like us account for only .05 percent of the IP addresses in the world. Wow.

• IP address is no longer the sole mechanism by which spam filters judge a sender. The domain address is once again being used in many cases when spam filters weigh the spamminess of your email. This has big implications for companies that use affiliate marketers or whose email programs lack any central control. All it takes is one rogue affiliate marketer to get your domain name thrown into the spam bucket and you could find your otherwise pristine corporate email program getting bulk-foldered.