I've posted about this problem before and at least glad to know I wasn't crazy in that it IS a consistent and real problem.
I thought it was entirely ridiculous that emailing was the only viable option for any person with an iphone, and refused to accept it.
However, my phone began restarting randomly like 3 times a day and Verizon sent me a replacement. One of the first things I tried was sending a pix msg to my iphone friends, and it worked and no one ever got back to me from Verizon about ALL my original malfunctions and genereal Eris weirdness... which sucks.
It has to be a glitch in the specific phones, and not the network since it doesn't seem widespread. Something I believe Frisco said in another thread about quality control of the Eris at certain factories rings more and more true (haha, pun).
Good luck, though, hopefully you can come to a resolution or decision.