Ways to cut back on spammers

So as much as I like all the new ways that I can get prescription drugs without one, they get annoying when they take over the recent posts box a couple times a day.

I don't know if these are implementable on this site, but I came up with some ideas that should be able to cut back a little bit on the spammers. I also forget the process for creating an account so some of these might be redundant. Also, some of these ideas are not mine and I've seen on other sites.

Require email verification before you can post.

On your first post, have a captcha to verify you aren't a robot. Instead of just a regular captcha it can be a captcha, but inside of it, a simple math question so that a bot can't just read it and output to bypass it.

After posting, you have to wait a minute to post again.

If you post x amount of posts within a minute, your username gets flagged for spam and can't post again until it is reviewed. (this obviously doesn't work if the above tool is implemented)

I don't know if this site uses them, but having moderators. Users that are on a lot, good post history, etc. and could be "paid" in the form of job board access or something. When the spammers do get through they'll be able to delete them quickly.

I had some more, but forgot them. I'll add them to this post when I think of them.