[SDL] SPAM prevention (Important!)

[Sam Lantinga]

We have changed the mailing list so it does not accept mail from addresses
that are not subscribed.

The good news is that we've caught 3 spam messages just today.

The bad news is that if you want to mail to the SDL mailing list, then
you must use your subscribed address as your return address.  Otherwise
the mail will bounce to my mailing-list trash can.

The news <--> mail gateway is also temporarily broken, but that should
be fixed soon, right Raf? :)

See ya!
	-Sam Lantinga, Lead Programmer, Loki Entertainment Software