Email append: Do you hate it?

Hi! Al Iverson here. I offered to guest blog for my friend Laura Atkins, as she’s off to a conference for a few days. If you like my posts, c’mon over and visit me at my blog, Spam Resource.
A few weeks ago, an industry colleague asked me why I’m so anti-email append. I’m not specifically anti-email append, I’m just not very fond of things that cause deliverability problems. And any time I have some huge, horribly complex client deliverability problem to deal with, the underlying source of the problem tends to be some sort of third party data thing, like email append or co-registration. It’s pretty straight forward, from my perspective. You’re sending mail to people who didn’t give you their email address. I know it’s legal, the ISPs know it’s legal. But the ISPs see that this causes spam complaints to spike, and they hate enabling delivery of mail that causes complaints, so it gets you blocked.
Email Append -> Add those addresses to your list -> You get higher spam complaints -> You get blocked.
Why does this happen? Why are these people complaining about my mail? This is a simple question to answer, too: Subscribers don’t want this mail. Most of the people who get this mail, they were not expecting it. They didn’t give you their email address. They’re surprised that you have their email address. They’re probably already getting a lot of unexpected mail (you don’t think you’re the only one who “appended” their email address, do you?), and they are experiencing inbox fatigue. Click, select all, report spam.
You have no idea what our subscribers want, you might say. Really? No idea at all? If you do this, and you find yourself  blocked, as you likely will, THAT RIGHT THERE IS AN EXCELLENT DATA POINT THAT SHOWS THAT PEOPLE DON’T WANT THIS MAIL. You’re making assumptions about what you think your subscribers want, and the data is telling you that you’re wrong. Listen to that data, learn from it.
If you don’t, you’re not going to have much success getting mail delivered successfully to the inbox.