fixes #7666, #7667, #7668 - errata mail notifications

We're a bit stuck there, it's the only option for some very popular web mail providers (e.g. Gmail).  We're lucky they're supporting CSS at all these days.

I did break some things out as partials, but even then, the styles are in-line on those tables too.

It could all be abstracted away to helpers or something, but the nature of e-mail notifications is that I don't expect the number of e-mail types to ever become more than a handful.