Technical setup guide, DNS records
DNS MX Records
Blank or @ MX 10 ASPMX.L.GOOGLE.COM
Blank or @ MX 20 ALT1.ASPMX.L.GOOGLE.COM
Blank or @ MX 20 ALT2.ASPMX.L.GOOGLE.COM
Blank or @ MX 30 ALT3.ASPMX.L.GOOGLE.COM
Blank or @ MX 30 ALT4.ASPMX.L.GOOGLE.COM
DNS TXT Records (General setup, secure)
Blank or @ TXT “v=spf1 a include:_spf.google.com -all”
* TXT “v=spf1 -all”
Blank or @ TXT google_random_code_string