Without question, email is a critical marketing channel. It varies in rank by study, but email is generally considered one of the top channels by ROI.

And that really shouldn’t come as much of a surprise. With high send volumes, CPMs are usually under $1. The more critical thing to consider is that someone who you’re emailing has already volunteered their information to you in some type of transaction – meaning by most definitions, they’re your customer. Getting an existing customer to transact is almost certainly going to be less expensive than acquiring a new customer. Compound that with the fact that other channels like paid search and display are simply more expensive on a CPM basis and it’s crystal clear why email has a high ROI.

So when you’re considering your top channels by ROI – is it really fair to compare email to other channels? My vote is no.