I just searched this forum for mms, and came up empty. I want to share something I learned, the hard way, to spare others the aggravation.

First, an FYI: Google Voice does not relate to MMS, period. No immediate warning appears. Rather, you send your message, and later discover the recipient didn't get it. I've confirmed this through several forums, including HowardForums. A half-hour to an hour later, a GV SMS lands in your box, telling you your message did not go through. Problematic, as several other SMS messages may have been exchanged during the interim. Lotsa luck figuring out which message GV refers to.

Second, what about sending an MMS straight from your assigned Verizon number? It's doable, but it can be tricky.
1) MMS can't be larger than 300kb. Best bet: use Handcent SMS. Easy to attach a pic, and a popup asks if you want to resize. Say yes, Handcent does its thing. But, there may still be a problem.

2) Droid has a bug. If the mobile number you're targetting has parentheses in your phonebook, the MMS won't go through. Again, no warning or alert to advise you of the problem. Fix-it instructions indicate that you should first delete all threads on the Droid previously sent to your target. Next, go into your phonebook, to that target mobile number, and remove the parentheses. Soft reset your phone.

Kicker: This may not be a permanent fix. STRONGLY suggest you read the HowardForums thread. Just wanna be sure you're aware of this stuff NOW, so you'll know what's up if you bump into this MMS-Droid bug.

(PS- Despite having smartphones for years, today = the first time I ventured into the send-MMS waters. Aaarrrrrggggh!! Good news: managed to do all the troubleshooting research exclusively with Droid & Dolphin browser )

References:
How to fix the Motorola DROID MMS bug | Gear Live

HowardForums: Your Mobile Phone Community & Resource - Droid MMS "invalid address" Glitch