NutshellMail, an fbFund REV company, debuted a useful feature for page admins this week allowing them to create an automated newsletter for their fans by adding an “Email Newsletter” tab to their pages with the company’s Facebook app.

This newest addition to NutshellMail’s features allows fans to opt-in to the newsletter with featured content from a page, per a company press release.

The new feature is designed to be easy to set up, use and maintain, and encourages subscribers to comment, like, share or post directly back to Facebook pages through the email newsletters. Although Facebook recently debuted a reply by email function, NutshellMail has offered the same feature since May of 2009.

The automated newsletter is similar to NutshellMail’s primary service, allowing users to compile social network updates from Facebook and others into a “snapshot email” which is sent to a primary email address on a schedule determined by the user —anywhere from once a week to hourly. Frequency, content and other settings for this snapshot email may be adjusted by users, who may also reply to notifications directly into Facebook and other networks via email.

In June of last year we spoke to NutshellMail’s co-founders David Lyman and Mark Schmulen, who said the allure of their company was that it allowed users to enjoy the perks of social networking without having to slog through piles of notifications.

“With Facebook, it’s easy to get annoyed of email notifications and most of them remain unread. By consolidating activity on Facebook – and even Twitter, MySpace, LinkedIn – we deliver email digests to users when and how often they want them. As a consequence, our email open rates are high,” they said.

NutshellMail released a similar application for Ning — the social platform allowing people to create their own social networks around causes, brands or interests that passed the two million mark this week — enabling public networks there to create an email newsletter for their site.