[ Thanks to Andrew
Weber for this link. ]
“Mailbox Size Limit
Default mailbox size is 50 MB. This means that if your mailbox goes
beyond 50 MB, you will need to adjust the default or you will see
the error, “File too large”. The limit for any local mailbox or
maildir is 50 MB but, this can easily be changed with by using this
directive in the main.cf file. Be sure to restart Postfix if you
make changes.mailbox_size_limit=102400000
“This changes the mailbox limit to 100 MB. Or you can make it
umlimited by using a “0″.”