Mail server settings can generate invalid main.cf

short description

System > Server Configuration -> Mail settings allow me leave "Message Size Limit" unconfigured when i specify"Mailbox Size Limit". This lead to misconfigured Postfix main.cf:

fatal: main.cf configuration error: mailbox_size_limit is smaller than message_size_limit

This also can have other consequences, for example Mailman cannot deliver emails to local transport:

to=<conf@localhost>, orig_to=<Conf@lists.domain.com>, relay=none, delay=414887, delays=414887/0.08/0/0.03, dsn=4.3.0, status=deferred (mail transport unavailable)

correct behaviour

ISPConfig should check if mailbox_size_limit isn't lower than message_size_limit and should notify user.

environment

Server OS: Debian

Server OS version: Jessie

ISPConfig version: 3.1.11