If your on of those people with LockMail crashing then you will most likely be on the 3.0 or 3.0.1 firmware. This is because LockMail was completed on 3.1 SDK and with a 3.1 device. As LockMail was started as a project on the 3.1 SDK i have not looked into downgrading my SDK them compiling for 3.0 as this would seem a large waste of time for me as most devices should have 3.1 or above as Apple also seems to have this shown in the App Store now.
So the way to solve your problem is simply upgrade to firmware 3.1 or higher - It will be better for you as well as it contains bug fixes and updates by Apple. Upgrading may require you to follow a method on iClarified for help.
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