add related object, mass mail utils

I added a generic foreign key field on Message in order to allow relating sent or received messages to any other object. For instance, I use this to process email replies to comment notifications. (I only added the south migration so far.)

I also added send_mass_mail functions (for text-only and multi-alternative with html) that store outgoing messages in the Message table and accept a related object to be stored in the aforementioned new column.
I see your point. If I find some time in the next couple of weeks, I'll
take a stab.

On Wed Dec 10 2014 at 8:49:06 PM Adam Coddington <notifications@github.com>
wrote:

> In django_mailbox/models.py
> <https://github.com/coddingtonbear/django-mailbox/pull/36#discussion-diff-21657981>
> :
>
> > @@ -413,6 +417,17 @@ class Message(models.Model):
> >          verbose_name=_(u'In reply to'),
> >      )
> >
> > +    related_content_type = models.ForeignKey(
>
> Awesome work, thanks for the contribution, @fsboehme
> <https://github.com/fsboehme>!
>
> As much as I love the idea of this, I'm a little hesitant to require a
> migration that'll add new columns to everybody's mail records -- the
> library has been around for quite a long time, and it's entirely possible
> that people have database tables with an inordinate number of records at
> this point; could I convince you into moving this into its own model, and
> instead using a ManyToManyField to relate those related objects with the
> Message record?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/coddingtonbear/django-mailbox/pull/36/files#r21657981>
> .
>