1. Many temporary email website exist.
2. You could abuse plus sign on email address. For example, alt+1@gmail.com, alt+2@gmail.com, ... , alt+999@gmail.com.
3. There are some service which offer lots or "unlimited" email alias. For example, Apple's Hide My Email.
4. It's annoying to register with an email address. Most websites require it, but would be so much better without it.
It looks like many websites (not only crypto-related) use the emailprovider as spam protection. So they reject temporary email providers and usually say "gmail+something" is invalid.
If there is real spam from newbies then admin can reduce posting limit to several posts per day instead of the 360 second limit but you need to prove that there is a heavily spam happening and it is harming the forum.
I think that this limit should be increased and thus make it as difficult as possible for these spammers.
Spammers will patiently wait, real users will be annoyed if they have to wait even longer than 6 minutes before they can post again.
It may seem like a "hostile move" to someone, but if the rules of the game are set as it is now, then we see that someone can write 4-5 or more posts with obviously dangerous links before being removed from the forum.
Links are only dangerous if the user does stupid things. To quote theymos:
Honestly, I think that someone that naïve can't be protected. Even if every inch of the page had been full of warnings, he still might've fallen for it, since he wasn't even thinking about the possibility of being given evil instructions.