Last week I had to delete/ban a total of 12 spammers ( some guest~some joined ) just to post their trash! Now, I have upgraded my security and made all registrations have to go through me before I let them loose on my board! There are plenty of boards available for Porn~ they DO NOT have to post on mine!
Yeah it is annoying when your forum gets spammed with all pornographic pictures. It has never happened to me although on forums I am a member of it has happened quite a lot.
Looking at your forum you are on invisionfree which is the reason why as they have no CAPTCHA of any kind making it easy for bots to sign up.
The only way to reduce them on free ipb hosts like invisionfree that don't have capcha is to make custom profile fields that are shown on the registration form and have to be filled it. If you make a field that says rate this forum then restrict the characters to just numbers (I think you can do that on ipb) then that should stop most/all of them.
I have had them on one of my old forums, my forum was a support forum for a program and i really wanted guests to be allowed to post, but i used to get too many spammers, so i had to restrict guests from posting.
Usually I just have spam members join occassionally. Lately though I've been getting some spam members that are actually posting. They sign up with legitimate names and then post with a legitimate thread title, but when you click on it, a page full of porn comes up. Naturally I'm not adverse to seeing it. I tend to be delayed in deleting it. hehe. But it's not something I want on my board. Luckily it only happens once in awhile.
Actually it's the largest Russian webmail site out there; kinda like a Russian hotmail, I think.
Thing is, I don't remember having any Russian speaking members signing up, and if they did (and they obviously spoke English), they would more than likely have an English email account as well that they could use!
We have one russian member here who uses gmail i think it was. I have seen a few other russians post an email address on forums but i have never seen anyone post a mail.ru.
Alot of people do ban mail.ru and in the lists you can get from various sites full or domains to ban to stop spam that is always at the top. It must be annoying for the people who use it.