

This project uses mDNS, which is specific to the .local
TLD. The whole reason that people are against the use of .local
is because it would break mDNS. So you can set a custom TLD, but it doesn’t matter because this is actually the correct context for .local
to be used, and changing the TLD will actually break things for a lot of clients.
I don’t get why they call hosting a mail server being your own ISP. It’s a very very loose definition of the term “ISP” there. ISPs may provide mail services on the side, but that’s not what makes them an ISP imo—its providing internet access that makes them an ISP.
On looking it up, apparently some people consider email providers ISPs in their own right though? Seems like confusing terminology.