Sprint has issued firmware YL10 for the Samsung MM-A900. This is a high-priority update which fixes Picture Mail as well as “other housekeeping issues”. In the update notes, Sprint did state that another update, following YL10, will be made available soon.
To update the MM-A900, go to Menu > Settings > Others > Update Phone. If you are still getting a 1012 error, power the phone off and back on, then try again.