@quanin the built in Captcha support filters almost all of it, I also manually review new users and IP block problematic subnets.
My server has been up for 3 years as open registration the whole time, on the Join Mastodon server list too, and there’s never been a spam problem.

if we can get someone on Fedi anywhere, that's 90% of the battle and they can slowly learn from there at their own pace 
