Comment 2 for bug 1430682

I saw your patch, that's similar to one I had submitted initially but Florian pointed out that it is not the right way(https://bugs.launchpad.net/postorius/+bug/1437866/comments/2)

So I submitted another patch, that now solves the problem and issues a proper ImproperConfiguration error instead of Attribute error.

First it checks the EMAIL_CONFIRMATION_FROM if that is not set than it checks for DEFAULT_FROM_EMAIL. If both are not configured than it issues a ImproperConfigurationError instead of the AttributeError, at least that helps in understanding that there is a problem in configuration and not the code.