Although only the summary is available for free, there are some important suggestions in the summary.
Here are a few highlights that caught my attention:
Length of time it takes to subscribe & unsubscribe:
"In our latest study, the subscribe process took 4 minutes, and the unsubscribe process took 1.5 minutes. Even though these task times are not prohibitive, they’re much too long for the simple functionality involved."
We recommend setting a usability goal of allowing an existing user to unsubscribe in less than a minute, assuming that the user has a recent copy of the newsletter at hand. New subscriptions should also take less than a minute when subscription requires only the user's email address. Even if additional information is required, users should be able to subscribe to free newsletters in less than 2 minutes. Only newsletters that involve a subscription fee should be allowed so many steps that the average user can’t subscribe in 2 minutes.
Does anyone read email newsletters?
"The most frequent complaint in our study was about newsletters that arrived too often. And, when we let them vent, the most frequent advice our study participants had for newsletter creators was to “keep it brief.”How often should you send email newsletters?
Newsletters must be designed to facilitate scanning. In our first study, 23% of the newsletters were read thoroughly. In our third study, four years later, only 19% of the newsletters were read thoroughly. The drop in percentage of thoroughly read newsletters is a good indication of the increased volume of email that users have to process."
"Users will often avoid signing up for newsletters because they feel crushed by information overload. It is the job of the newsletter publisher to convince users that the newsletter will be simple, useful, and easy to deal with.
A predictable publication frequency that is not too aggressive is usually best, except for newsletters that report breaking news. A regular publication schedule lets users know when to look for the newsletter and reduces the probability that they’ll confuse it with spam and delete it.Also, writing good subject lines is crucial, both in encouraging users to open the newsletter and helping them distinguish the newsletter from spam. We recommend including content from the issue in each subject line, even though it's a difficult job to write good microcontent within the fifty- to sixty-character limit that many email services impose."