@davidochobits mentioned NethServer in the video chat and in the comments as an option to build your own mail server (spanish language):
Great "spread the word" post by @robb https://gathering.tweakers.net/forum/list_message/52246679
And a nice graphical tutorial
Thanks @FixitFelix for this https://community.spiceworks.com/topic/post/7172605
It's the best tool for the job he needed! The thanks should go to the there devs, you and the community!
You really deserve this with @vhinzsanchez another NethServer evangelist on Spiceworks
Thanks. Had been struggling with our internet here. Our ISP has had a major cable trouble so had to live for 3 weeks without our main internet, atleast at work. The backup internet is not just enough to accomodate our traffic today.