Postbox 4 was released last week, and it’s good. Yes, I’m way behind on blogging, but that’s another post.

Postbox has long been of interest to me because it offers stability and a degree of extensibility. I’ve settled into MailMate quite nicely in recent years, but the new version of Postbox looks amazing, and is a great option for people who need a level of power that falls between and MailMate.

First, the new version is pretty. Postbox has always achieved a certain level of aesthetic beauty that defied its origin as a Mozilla-based email client. This version, though, is stunning.

The “Focus Pane” that has been part of Postbox for a while now has received a powerful update. It provides a way to find messages using common criteria such as recipient headers, attachment attributes, and custom labels. The criteria can be quickly combined into powerful searches. I like this because it’s as powerful as many of my Smart Mailboxes, but simplified from a setup and modification perspective.

Postbox 4 also adds Box and OneDrive to its cloud attachment capability, which lets you have your email attachments automatically hosted on a cloud server to avoid sending large files through your email host and into your recipient’s inbox.

The “Domain Fencing” feature is new, too, and something I haven’t seen implemented anywhere else before. When composing a message or reply, it can intelligently warn you if you’re sending it to someone outside of your organization when you shouldn’t be, and if you have multiple accounts it can let you know if you’re replying from the “wrong” account.

There’s a lot more to check out, and you can read the full release notes, but if you’re in the market for a powerful email client, I recommend just giving it a shot.