I just installed the trial version, and three times now my Apple Mail client suddenly shows no messages whatsoever in any folder (I have many thousands of messages and probably 100+ folders). When I quit Mail and restart, they are back again.
The first message I sent to try it out was classed as spam, even though it was from another account of my own, appears in my address book, etc.
I’ve never heard of that problem before. It’s possible that installing SpamSieve had the side effect of activating a dormant Mail plug-in that’s causing this problem. You could check the folders:
and see if there are any plug-ins there besides the SpamSieve one. To disable a plug-in, drag it out of the Bundles folder and restart Mail.
There are a variety of reasons, including setup problems, that a message might end up in the Spam mailbox. Please check the log to see whether SpamSieve actually thought that the message was spam. By default, SpamSieve is set to ignore your own addresses in the address book, so if SpamSieve did think that the message was spam, that’s not a bug but rather due to insufficient training.