What should I do about a lookalike with MX?

Check who registered it and whether it hosts a site. If it is clearly imitating you, report it to the registrar's abuse contact and, for .uk names, to Nominet. Registering the closest variants yourself is cheaper than the incident.

Lookalike domain finder

Typos, homoglyphs and other endings of your domain, with which ones resolve and can receive mail.

What this check does

Generates the variants people mistype or attackers register: dropped and swapped letters, adjacent keys, 0 for o, rn for m, login- and secure- prefixes, and the same name under other endings. Each one is resolved and checked for mail servers.

Omission, transposition, replacement, insertion and repetition typos
Homoglyphs and hyphenation
Brand-plus-prefix names (login, secure, support)
Alternative endings (.com, .co.uk, .uk, .net …)
Which variants resolve and which have MX records

Questions

What should I do about a lookalike with MX?: Check who registered it and whether it hosts a site. If it is clearly imitating you, report it to the registrar's abuse contact and, for .uk names, to Nominet. Registering the closest variants yourself is cheaper than the incident.