Email snarfing

I've recently encountered a number of email problems (delayed delivery, lost mail, etc.) both from my pop accounts and Hush. I'm not trying to be paranoid but could these be caused by problems of TLA-installed transparent SMTP, POP, and HTTP proxies at ISP's in a man-in-the-middle mode, so that they'd be sure to see all traffic, because Carnivore's storage capacity is pretty limited? Also, if missing email causes a sender to re-transmit the same message could this expose the message to some sort of replay-resend attack if the crypto isn't well coded?