This app is no longer maintained. Originally written for 4.4. No idea whether still works on recent Android versions.
USE AT YOUR OWN RISK
This one has a killer feature supports optional filtering by sender: filter can be configured either as a blacklist (to forward messages from senders not in list) or as a whitelist (to forward messages only from specified senders).
Usage and configuration should be straightforward enough. Please note the app requires some configuration (at least a phone number to forward to).
Uses an icon from Blue Bits pack by IcoJam.