Pardon me sir, but in my case this would not work. The problem was due to some messed up ownerships in /var/mobile/Library/Mail - which also exist in my backups. I suppose I could have restored and then clicked "new iphone", but that would very much be a last resort.
I managed to remedy the problem by SSHing and running the command:
"chown -R mobile:mobile /var/mobile/Library/Mail"
Should this ever happen to anyone else, here's a good site:
http://www.ben.geek.nz/fixing-iphone-mail-crashes-20-firmware/
PS - thanks Warbrain, you got me on the right track.