Hi, for what I remember every time I tried to use MobileMail app I was never able to use it because it said that a password was required to log into my mailbox... but when I wrote my password under Setting app, and go back to Springboard, the password disappeard. And so now too, it won't save my email password. It seems like it can't write on the password's file..
What should I do?

Seems like a permition problem. Unfortunatelly I don't know the exact file path , but I would suggest determining it's location and making sure it's attributes allow +rw same goes for directory where it sits.

You could also try with +rwx.

Yes I've already tried
chmod -R 777 /var/mobile/Library/Mail
but... nothing

You could also verify /Applications/Mail.app owner vs /var/mobile/Library/Mail owner.

Uff, I did a restore on my iphone and Mail worked perfectly then. But now I installed some packages on cydia that should have modified something related with the app, and my email password's still not saved

As far as I remember BossTool did allow to move Applications to Media Partition. Perhaps you need a symbolic link in the original location pointing to the new one.

No, i'm sure.
I'll try to find out what package give me this error.

bah... Mail app works again.. don't know why