An SPF record is a type of Domain Name Service (DNS) record that identifies which mail servers are permitted to send email on behalf of your domain. The purpose of an SPF record is to prevent spammers from sending messages with forged From addresses at your domain.
Example of SPF record set up through GoDaddy using Gmail
v=spf1 include:_spf.google.com include:infusionsoft.com ~all
DKIM (Domain Keys Identified Mail) is a complex email protocol that allows a sender's identity to be authenticated by the recipient to help combat email fraud.
You can add additional email domains by adding that email domain to a User Record.