SWEET!!!!
HAHA...after tinkering with a few different cabs, I've finally got MMS to work on both EnergyRom 2.1 and 2.5 for TP2s on Boost.
This is what worked for me. After flashing the rom that you want, install the StockBoostMMSfix.cab, soft reset, after TP2 boots u-send yourself/someone a MMS. It'll show the sending icon first, then the check mark, and it'll go through. That's it.
Hopefully this will help some you who are on Boost and want to try different roms. I can't seem to find the thread where DaddyMikey1975 posted the cab for the StockBoostMMSfix, but it's on the forum here, somewhere.
Thanks to the guy that created that cab and DaddyMikey1975 for posting up the cab.
If this helped you in any way, hit the "Thanks" button.