MMS Problem with IOS 4.2.1 iPhone 4 Beijing China

Just upgraded from 4.1 to 4.2.1 and got problem sending out MMS (pictures).
I tried to change the setting under Network - Cellular Data Network - MMS - MMS Max Message Size to 800,000, then succeeded. But when changed back to 50,000 which is the regular size of MMS here, it just did not went through.
So seems the problem is after upgrading the phone cannot resize pictures automatically. When the 800,000 bytes picture went through, it did look prettier and sharper when I checked by clicking it in the message thread. The ironic thing is, 50,000 bytes is the limite of our local service provider, China Mobile. So I will not be able to send out MMS from my iPhone unless it is sent as the original size, and once I sent it out without resizing it, my friends get a text from China Mobile that they cannot get my MMS cause it is over-sized... (@v@)
I found this happening in other countries as well, so guess we just wait for Apples solution :S And for people that using the service with no size limite of MMS, changing the setting as I did above may solve this problem, temporarily...
iPhone 4 iOS 4