Originally Posted by Motorcycle Mama
If it's less than 12 000 000, then the phone will start to delete messages.
That's really not accurate.
There's no documentation that say 12MB is the cutoff for the device to start deleting old content to make room for new.
We have users that run their devices with 4 or 5 megs of free memory and never experience any data loss.
A better answer is that the device will start to purge old messages when it thinks it needs to.
It's not always 12mb.