Yes, 721q.org can receive emails.
Yes, 721q.org seems to be a legitimate domain.
A record
91.195.240.103
MX records
ALT1.ASPMX.L.GOOGLE.COM
64.233.186.26
ALT2.ASPMX.L.GOOGLE.COM
209.85.202.27
ALT3.ASPMX.L.GOOGLE.COM
74.125.206.27
ALT4.ASPMX.L.GOOGLE.COM
74.125.128.26
ASPMX.L.GOOGLE.COM
173.194.175.26