How one can effectivelly prevent SPAM on IPB (invision powerBoard)?

PM (personal message) SPAM

So far i know i can effectivelly limit number of PMs sent by member (ACP > Members > Member Groups > Manage Member Groups > "Click on a Group you want to apply PM limits too" > Global Tab > Personal Messages)

Registration/posting SPAM prevention

one may use module to disallow known spam bots to register at all:
(i used first link and it seems to work, but still some spams go thru) here is backup file of that module: (JG33)
One need to extract downloaded .zip, find upload directory in it and upload it. Then in IPB Admin / System / Applications & Modules instal the module. After that click Other Apps menu entry on the top. Then modiffy this module settings.

2) in admin area add captcha into the search field. And find recaptcha in results and here enable recaptcha or keycaptcha.