Well I've found that on any network, just setting yourself to invisible mode (which I'm sure is standard on all ircd's as +i), has always allowed me to evade unsolicited spam messages from people who aren't just using remote triggers to send people messages upon joining a channel.
Though this may not block all spam you receive, I'm sure it will help cut down on a heck of a lot. I haven't received anything for years, unless it's due to somebody's remote script upon joining a channel.
