3210 did not support MMS, but EMS with some semi-proprietary extensions. Sending images and ringtones over EMS was generally not interoperable between different vendors.
MMS is much later technology where the user data go over HTTP, which implies at least WAP support and GPRS to be really practical.
You are totally correct - I was thinking of 'picture messages' which this could send. I was only a little jealous of the 3210 as i thought it was quite ugly really, but the 3310 seemed a heap better, especially with the blue led (which is what sold me on the 8250).
MMS is much later technology where the user data go over HTTP, which implies at least WAP support and GPRS to be really practical.