Т.е. ты свято уверен, что МХ записи смотрят именно на mail.google.com и его алиасы... нуну!

nslookup -type=mx google.com

CUsers\wsdx>nslookup -type=mx google.com
Server: ns2.oda.local
Address: 172.16.2.1

Non-authoritative answer:
google.com MX preference = 40, mail exchanger = alt3.aspmx.l.google.com
google.com MX preference = 10, mail exchanger = aspmx.l.google.com
google.com MX preference = 30, mail exchanger = alt2.aspmx.l.google.com
google.com MX preference = 20, mail exchanger = alt1.aspmx.l.google.com
google.com MX preference = 50, mail exchanger = alt4.aspmx.l.google.com

google.com nameserver = ns4.google.com
google.com nameserver = ns2.google.com
google.com nameserver = ns3.google.com
google.com nameserver = ns1.google.com
ns1.google.com internet address = 216.239.32.10
ns1.google.com AAAA IPv6 address = 2001:4860:4802:32::a
ns2.google.com internet address = 216.239.34.10
ns2.google.com AAAA IPv6 address = 2001:4860:4802:34::a
ns3.google.com internet address = 216.239.36.10
ns3.google.com AAAA IPv6 address = 2001:4860:4802:36::a
ns4.google.com internet address = 216.239.38.10
ns4.google.com AAAA IPv6 address = 2001:4860:4802:38::a