This is not true
"As it was mentioned by Anonymous generaly is a very bad idea to use mail server on a broadband connection"
Rubbish. I have a mail server, very similar to what is being proposed in the article, running at home. It is also an FTP Server, Cloud Server, Media Server, Shared folder server, etc. It runs on Broadband, is behind a firewall, and has a dynamic IP.
It simply works. Has done for years. It got fried by a power spike and took less than a day to recover from the encrypted backups on Amazon S3.
It doesn't get any problems with Google, Amazon, Hotmail etc. It gets tested once a week to ensure it is not an open relay.
And it hosts multiple mail domains easily.
Why do this? Because its my data, in my hands. If any three letter agency wants access, they have to come to me to get it, so I will know.
Just because you couldn't set it up yourself is not a reason to tell others not to try.