Mailsmith is a valid mail client for the MacOS. It’s a Carbon application,
like BBEdit (and in fact they are both made by the same software house)
Mailsmith is different from other mail clients. It does not support HTML messages (and that is good, not bad). This is not perfectly true, in fact the engine is able to convert HTML messages to a text representation and makes it easy to open them in a full fledged web browser.
Mailsmith has powerful filters for handling mail. Rules can be AND-ed and OR-ed (in this is superior to Apple’s Mail). In Mail you can only OR all rules or AND all rules. That is to say all you can do is
rule 1 AND rule 2 AND rule 3
rule 1 OR rule 2 OR rule 3
If you wanted to do
rule 1 AND rule 2 OR rule 3
With Mailsmith youcan. For example you want to filter mail containing in the subject “[Python]”or coming from “*@python.org”and containg the word “Twisted”.
Mailsmith has a powerful searche engine. It is fast and has many options. In fact resembles the find dialog found in BBEdit (and that is one the more powerful I have seen).
Unfortunately right at the moment it appears not to support spotlight (and spotlight does not support Mailsmith mailboxes, as far as I know). This is in my opinion a major drawback of Mailsmith. Spotlight is a core technology in MacOS X and is going to gain more power and more importance.
Generic system integration
System integration is sufficient if not good. It works well with Address Book, but as I said before it does not support Spotlight.
Imoport and export are easy and efficient. You can import a mbox dragging it from the finder to a Mailsmith mailbox. You can also export mailboxes and messages with drag and drop (for eg. in Mail.app you cannot drag a single message on the desktop and have a message file created).
Mailsmith antispam system consists in a tight integration with SpamSieve. That is a very good system, in my opinion. However, what amazes me is the integration with SpamCop, that easily allows to report spam with a single click.
Mailsmith is an excellent Mail client, still it’s not something for everyone. It’s a bit geeky in its features, but it’s great.
Still it costs lots of money. I’m afraid I’ll switch back to Mail.app, not as powerfull, but more promising, in my opinion. Moreover it’s Cocoa.