tklapp.com (and probably custom) domains on the Hub shouldn't allow underscores #1516
Description
Currently the Hub allows user of underscores in a tklapp.com domain (and I suspect in custom domains too). E.g. my_domain.tklapp.com.
Whilst domain names with underscores appear to be legitimate, hostnames that include underscores aren't. Also, as of 2018 there are restrictions on domains with underscores, such as you can't get an SSL cert.
So bottom line, they won't work properly so they shouldn't be allowed.