Anyone have problems sending pics taken on an 8310 (i guess 8300 would be the same) via MMS to another carrier?

I took some pics and sent them to a friend on Verizon and TMobile. I got no send error and yet they didn't get them.

Later (4+hours) they got some but not all. My first thought was size, but the ones they eventually got were bigger in size than ones they did not.

Anyone have this same issue?