Ok, replace "spammers" with email-harvesting bots.

Okay then, despite what you think, it still prevents most of them.

I would say some not "most". vBullentin already has a contact form that spam bots cannot harvest user emails from. Condoning users posting their emails in posts (even in the manner described) is not responsible IMO.

Think about it, if were running a spam bot, wouldn't you work/design around such obvious tactics?

I guess I am not the only one around here who is not a programmer, and I actually posted here because I hoped someone would have the courtesy to post a complete explanation of how to set this up.

I'm only telling you to read up on regex because it wouldn't expand any of your knowledge if I did everything for you.

Actually, I have some limited knowledge about regex, but I have no idea where or how to enter the corresponding formula in vBulletin to make it change the posting text automatically.

You would need to add a plugin hooking at postbit_display_complete. The message's variable is $post['message'].

Seriously, if I would know how to add a plugin hooking to a template, I would very likely not have posted this question here in the first place ;)

Sometimes you just need to look......Admin CP > Plugins & Products > Add New Plugin.

Dismounted, if you know how to do this why not simply tell tobias_t rather than playing cryptic messages? Or perhaps you yourself don't know?