The best way to secure yourself against sniffing is to use encryption. While this won’t prevent a sniffer from functioning, it will ensure that what a sniffer reads is pure junk (unreadable text).

Yahoo Messenger does not support encryption. As a result of that, Instant Messaging conversations can be intercepted and logged.
Rocksyhoo provides encryption for Yahoo Messenger. Rocksyhoo will encrypt each message before it is sent and will decrypt that message after it is received on the destination computer. Both users must have installed Rocksyhoo and use the same password established by agreement in private.

Welcome back!