A look at diversity of MX records across all gTLDs and the Top 1M domains, indicating where SMTP is concentrated and what organizations might have broad access to the world's emails.| www.netmeister.org
The common definition of a 'valid hostname' is often reduced to a simple regular expression, but as the saying goes: 'Now you have two problems.' Because hostnames are DNS labels and those... well, it's the DNS. All bets are off.| www.netmeister.org