MailSmith is not for everyone. In many ways, it's the polar opposite to Apple's Mail, eschewing the likes of HTML support and a refined, simple interface, in favour of a powerful and configurable, entirely text-based workflow that has a tendency to occasionally litter your screen with windows.
At the higher end of the scale in terms of cost, MailSmith is designed to appeal to a core market of users who live by email - the kind of person who literally deals with hundreds of emails every day, and hasn't the time to wait for sluggish software. To that end, it has one of the most powerful filtering systems around, with a massive range of criteria and actions made available to the user.
Searches are similarly powerful, using the same search engine found in BBEdit. BBEdit's Text menu is also included, enabling you to rapidly edit characters, breaks and wrapping, and to zap gremlin characters.
Unfortunately, for all its power, MailSmith has some glaring omissions. We're not talking about the lack of HTML support here - it's clear that the majority of MailSmith users see this as a boon rather than a shortcoming, and HTML-based emails can always be opened in a browser.
What we're more concerned about is the lack of IMAP and Unicode support, the latter of which renders the application useless for those working in a multi-language environment. The interface could also do with some spit and polish - it can get windowheavy and cluttered - and the lack of support for message threading will put off some users otherwise intrigued by the program's efficiency and power.
If these issues don't concern you and you're regularly swamped by email, MailSmith could be what you need.