From the archive. We first published this in August 2010. Apple has since changed the way Mail add-ons work, so some of these tools have been rebuilt, renamed or retired. Check each developer's website for a current version before you buy.
Apple's built-in Mail app is great for most people as it is. Busy business owners often want a little more help staying organized, keeping the inbox under control and getting things done. Mail's add-ons make that easy. Here are a few of our favorites.
MsgFiler
This small, popular add-on does one thing. Press a single keystroke and a window pops up so you can file the selected messages into any mailbox. It sounds minor, but it saves a surprising amount of time compared to dragging and dropping, especially on a laptop trackpad.
Mail's smart mailboxes let you view messages that match certain criteria. MsgFiler is different: it lets you file whatever you have selected, quickly. It was shareware, and the $8 registration removed the reminder.
Mail Act-On
Mail's rules run when a message arrives. Mail Act-On takes that further by letting you assign a keystroke to any action you define. Do you regularly forward messages to an assistant? Send them to a task manager like OmniFocus? Log them in a ticket system? Mail Act-On turns each of those into a single keystroke.
It is especially handy if you practice Inbox Zero and sort every message into an Action or Archive folder as you read it. It is easy to set up without a programmer, and the developer offered good tutorials. It was free for 30 days and $24.95 to register.
MailTags
If you have ever liked the way Outlook or Entourage lets you link messages to projects and add notes, you will like MailTags, from the same developer as Mail Act-On. You can tag messages with projects, comments, reminders, contexts and due dates, find them with Spotlight, and build smart mailboxes around any tag. New messages in a thread pick up the tags from earlier ones, and the tags stay with a message when you move it into EagleFiler, OmniFocus or DEVONthink. It was free for 30 days and $29.95 to register.
Bonus tip: winmail.dat attachments
Do you have clients or vendors whose messages always arrive with a mysterious winmail.dat attachment? Their usual answer is for you to work it out with their IT department, which rarely goes quickly. The simpler fix is TNEF's Enough, a free utility that decodes these files. Save the winmail.dat file, open it in TNEF's Enough, and you get the real attachment back.
More add-ons
At the time, the Hawk Wings blog kept a well-described list of Mail add-ons, including all of these and many more.