A doppelganger is a domain name that is identical to a homogeneous domain name (FQDN), but does not include the dot between host / subdomain and domain.
Typosquatting’s traditional attack vector is through the web to deliver malware or harvest credentials. Other services such as SSH, RDP, and VPN also can be leveraged. In a whitepaper by Godai Group on doppelganger domains, they can show you many emails. 
If someone’s email address is “firstname.lastname@example.org”, the doppelganger domain would be “financesomecompany.example”. Hence, if someone is trying to send an email to that user and they forget the dot after “finance” (email@example.com), it would go to the doppelganger domain instead of the legitimate user.
- Anticybersquatting Consumer Protection Act (ACPA)
- Domain Name System (DNS)
- Uniform Domain-Name Dispute-Resolution Policy (UDRP)
- Jump up^ “Doppelganger Domain whitepaper” . Godai Group . Sep 6, 2011.