i know this is an old thread, but the "factory" picture mail is horrible for all of sprint's windows based phones imho. I'm not sure if I can post any links or not, but there is an amazing app that has lifetime updates for $5 (donation through paypal...I assume some kid built the program haha). easy install and fast to send picmail. I used it on the ppc6800, the diamond, the touch, and the touch pro with 100% success rate and great speed.
I know it sounds like I'm trying to sell something, but I am not. if it's ok to post the link just let me know, or PM me