I guess it’s a combination of things really…
size and audience probably is a big part of why some sites are targeted more than others … there’s also the fact that some sites are easier to spam compared to others.
There’s nothing we can do to stop spam but we can make it difficult for them.
The first thing spammer do is try to get in automatically via bots. If that doesn’t work they will do it manually. If they believe the effort is worth it they will do it MANUALLY.
Register. Confirm. Post. Repeat.
For those looking for a solution maybe this will help…
A little background…
We are a large site - almost 1 million professional and student members. We require email address and confirmation when registering.
We do not have a captcha but do have a unique “registration” process that is constantly changing. The goal is to make it difficult for bots but not for our readers. It seems to be working.
For spammers that do get through we’ve built some obstacles for them.
For starters, all new members are throttled. Submitting anything requires xx minutes (floodtime) of wait time between posts. (This applies to new members only.)
This step will not stop all the troublemakers.
So what can we do???
At this point I decided to automatically set all posts with a link to moderation. Keep in mind that most members are here to ask questions not to share links. 100% of the time spammer exists to share links.
This moderation step continues for the first xx number of posts submitted by new members.
The idea behind this is to give our moderators plenty of time to review and ban the spammer before their messages become visible to the community (when the above obstacle no longer applies).
We also filter posts based on certain keywords/phrases (set to moderation).
There are a few more obstacles but that’s the gist of it.