This is not for data users. I tested the data by sending several mms emails the emails were 1.6KiB, 1.5KiB, and 7.4Kib in size. I got hit with a 1MiB charge (5 cents) for each email! Maybe everyone else does this but this seems extreme.
Anyway I turned the data off completely in my account settings. I don't need data on these accounts.
Just a warning to folks that are using data make sure you use at least a 1MiB at a time because you will get charged that much even if you use less than 1MiB.