Agree totally, vordmeister, and I hate having to do it.
Before my post in July (linked in the first post) I'd re-enabled GMail for that very reason. One hour after doing so, someone with a GMail email address spammed the forums. That continued remorselessly across the next week or so until I threw in the towel and banned them again. Now, with SFS [stopforumspam.com], not only is GMail available, but even mail.ru & several other email domains that previously made me shudder. I now look forward to seeing a spam email! It means that I can ban them for the community, and not just myself.
GET list frequency on the SFS reports (`how often reported') are frequently in double-digits. That is most unlikely to be an 'innocent blocked'.
One more feature: having got spam posts under control, I found 2,000 'silent' spammers. They are registrations with personal details full of (the usual) links, but no posts. Those links are still polluting my Google SERPs, since G picks up each registration and browses the profile. Well, no longer. After some Control Panel code-changes I'm able to report them as well, and remove them.
Finally: for best, Google should have put this in place themselves, or have coordinated it between all email providers, and especially free-mail providers. Their lack of action suggests that they do not care. SFS provides a viable solution.