Stephen’s recently been questioned a bit about his email address validation regex – which has a few problems… Notably, it doesn’t allow for addresses like rob@uk, which I’m assured once existed (although I don’t believe it still does).

He wasn’t aware of any TLDs with MX records – so, of course, I had to set out to make a list. And here it is! The following TLDs (all ccTLDs, though I checked all the gTLDs I could find too) all had MX records, as of tonight

.ai – Anguilla
.as – American Samoa
.bj – Benin
.cf – Central African Republic
.cx – Christmas Island
.dj – Djibouti
.dm – Dominica
.gp – Guadeloupe
.gt – Guatemala
.hr – Croatia
.io – British Indian Ocean Territory
.kh – Cambodia
.km – Comoros
.mh – Marshall Islands
.mq – Martinique
.ne – Niger
.ni – Nicaragua
.pa – Panama
.td – Chad
.tk – Tokelau
.tl – East Timor
.ua – Ukraine
.va – Vatican City
.ws – Samoa