Spam isn't really a problem for email lists you have to sign up for unless you have a really large number of subscribers. Spammers need zillions of addresses to make it worth their while to do anything.
Yes, the anti-SPAM efforts have made running your own Mailman (or other list service) instance an increasing pain. Many providers now silently drop list email, even if you have jumped through all the approrpiate hoops.
