Alternative prim communication?

I'm looking for an alternative method of communication between my prims. How efficient is e-mail.. or better still, is it possible to instant message an object?

currently I'm using negative channels, but I'd like something more secure?

Assuming the prims are unlinked (in which case llMessageLinked would be the obvious choice), there aren't many options. llEmail comes with significant delays and substantial overhead (but can cross sim boundaries). There's no inter-object IM. For security, encrypted random-channel chat may be an option, if throughput is low enough. (Or conceivably some web service intermediary via llHTTPRequest, but that's a whole different kind of "security" issue and not without overhead and numerous "moving parts" subject to failure or delay.)

you got
llRegionSay(integer channel.string msg) if the prims are in same region
you can also set up a web comunications and xml (not stabel with the down time xml service have from LL's side)
but take a look at

http://wiki.secondlife.com/wiki/Category:LSL_Communications