主机记录 MX 服务器地址 优先级
@ MX ASPMX.L.GOOGLE.COM. 10
@ MX ALT1.ASPMX.L.GOOGLE.COM. 20
@ MX ALT2.ASPMX.L.GOOGLE.COM. 20
@ MX ASPMX2.GOOGLEMAIL.COM. 30
@ MX ASPMX3.GOOGLEMAIL.COM. 30
@ MX ASPMX4.GOOGLEMAIL.COM. 30
@ MX ASPMX5.GOOGLEMAIL.COM. 30