Well, because i uses a GPRS connection to send the MMS picture message, this
requires at least a decent signal. It may fail once, so it'll try again. It
also means you know if it's been sent or not... You should really make sure
'save sent items' is checked then you know if it's been successful, meaning
you don't have to watch the screen just to ensure the thing's sent.

MMS is actually using WAP you know, it doens't actually send the picture
like a text message; it uploads it to a server on your network provider's
internal intranet space, then the link someone on another network (or the
same network gets) will have a unique URL (web address to you and I) in
which they're phone will try to connect through GPRS to this unique address
and download the picture.

The uploading can go wrong sometimes, so it can take a couple of attempts.

Peter Brown reckoned that...

It will go automatically. If it's not moving anywhere it means either
your account is not configured for MMS or there are some settings
missing from the handset.