Support for self signed certificates and using a different domain for email accounts vs internal domain

[paz]

I'm not very good with python, so I'm not sure if my code is very good. I've tested it on my setup and it's working nicely however.

The domain replacement is quite simple, it just replaces the domain if another is defined. The self signed certs aren't done by just ignoring validation, the container will run update-ca-certificates and you would have to add your certificates to the host and then uncomment the volume. None of these features are enabled by default, users will have to uncomment them in docker override yml.

[Programmierus]

Hi! Thanks for your effort! I am currently damn busy on another project, but deadline is soon. Have placed it on top of my TODO to check your pull request and also other issues with this project.

Thanks again.