[jeffasinger]

What I would do in your situation is try to measure the incremental value of future messages, the likelihood that a given message causes an unsubscribe, and the value of the current message to come up with a good balance.

For a small list like this, it may mean separating users into two segments:

* Actively engaged, send them a weekly update

* Not engaged, only send them big new announcements.

Marketers tend to look at link clicks, email opens (measured via embedded images), and engagement with the actual product (if you have it) for segmentation like this.