S/MIME encrypted e-mail in Mac OSX/Panther - how secure?

I’ve been thinking fro some time of starting to use encrypted e-mail–and, coincidentally, I’m probably going to buy Mac OS 10.3 (Panther), whose Mail program supposedly has S/MIME encryption.

Now, I read up a bit on S/MIME–it was put out by RSA, who basically invented public key cryptography, which is reassuring. But many old documents (1997-1999) I discovered on the Web indicate that, while a lot of mail programs use S/MIME, they only use a 40-bit key, which totally bites. (At least, they did at the time of those articles, so everything could be different now.)

Does Mac’s e-mail use 128-bit encryption? I would assume so, since nearly every US web browser now uses it for SSL, but I can’t find any specific documentation from Apple on the key length.

A quick search of Apple’s website shows that the only place 40-bit encryption is used is for their Wi-Fi networks. Everything else appears to be 128-bit encryption.

Super. Thanks.