SPF
1. You declare txt record in dns of domain such as:"v=spf1 include:_spf.google.com ~all"
Dkim
1. Login google app with account admin https://www.google.com/a/cpanel/domain.xxx/Dashboard 2. Advance tool
3.Set up email authentication (DKIM)
4.Do follow instruction of google about declare on DNS and verify
Nguyen Si Nhan