Is it possible to have one (single) character top level domain name?

Question

I\'m writing a Regex to validate email. The only one thing confuse me is:

Is it possible to have single character for top level domain name? (e.g.:

Answer 1

You should DEFINITELY allow 1-character domains since some registries allow them not by accident (and I speak of quite big registries like UK, Germany, Poland, Ireland too - so important contributors to the Internet community, not oney exotic small exceptions). Since I also plan using such domains, that definitely work also with all e-mail services I used, letters AND numbers, I really would give the hint to allow this, else your script might need later correction.

Also some of the biggest internet companies use such domains - one of the most famous examples is Twitters t.co for shortening. Other companies I know of who have such domains are Facebook, Google, PayPal, Deutsche Telekom. But the list is longer and also some bigger investors hold them as assets.

By the way as proof there is a website trading this kind of domains online if You search for "1 letter domain names" :)