How to find out the email host of a vanity email address?

Question

Assuming a person gets his own domain address, say, theperson.com.

He then goes on to create a vanity email address with that domain. e.g. [email protected].

[email protected] may be hosted by the person's own mail server, or somewhere else that offers vanity email services, such as Gmail, Yahoo mail etc.

To the uninitiated, using a commercial email service is useful as the service is already set up and running, and provides a more secure and stable environment compared to setting up a personal mail server from scratch.

So for an outsider, how do we find out which email service a person is using? Can I find out that [email protected] is actually hosted by Yahoo, or some other service?

Answer 1

The easiest way would be to use one of the online MX (Mail Exchanger) record lookup tools, for example MX Lookup on MX Toolbox. On Linux, you could also run dig stackexchange.com mx. Obviously, you'd replace stackexchange.com with whichever domain name you're interested in. On Windows, follow instructions from @Stephane for the command prompt syntax.

Answer 2

Check the MX DNS record associated with the domain name.

e.g (under Windows, for @stackexchange.com):

O:\>nslookup
Default Server:  **********
Address:  **********

> set type=mx
> stackexchange.com
Server:  **********
Address:  **********

Non-authoritative answer:
stackexchange.com       MX preference = 1, mail exchanger = aspmx.l.google.com
stackexchange.com       MX preference = 5, mail exchanger = alt1.aspmx.l.google.com
stackexchange.com       MX preference = 5, mail exchanger = alt2.aspmx.l.google.com
stackexchange.com       MX preference = 10, mail exchanger = aspmx2.googlemail.com
stackexchange.com       MX preference = 10, mail exchanger = aspmx3.googlemail.com

aspmx.l.google.com      internet address = 74.125.136.27
aspmx.l.google.com      AAAA IPv6 address = 2a00:1450:4013:c01::1a
alt1.aspmx.l.google.com internet address = 74.125.143.27
alt1.aspmx.l.google.com AAAA IPv6 address = 2a00:1450:4010:c03::1a
alt2.aspmx.l.google.com internet address = 74.125.25.27
alt2.aspmx.l.google.com AAAA IPv6 address = 2607:f8b0:400e:c03::1b
aspmx2.googlemail.com   internet address = 74.125.143.27
aspmx2.googlemail.com   AAAA IPv6 address = 2a00:1450:4010:c03::1b
aspmx3.googlemail.com   internet address = 74.125.25.27
aspmx3.googlemail.com   AAAA IPv6 address = 2607:f8b0:400e:c03::1b
>

-> Google