I'm at work right now and can't test again, but if you were to try this, does it still have problems?
Connect network 1
Disconnect network 1
Connect network 2
Disconnect network 2
Connect network 3
If that works, then it probably is something to do with limiting the number of times it will be sent to someone in a short time frame on that network as you suggested. If that still fails, then I'm not sure what would cause it.
