Authorized Email Domains

To send email on behalf of your users, Salesforce requires that you verify ownership of your email domains. We recommend that you set up DomainKeys Identified Mail (DKIM) to complete that requirement. If you can’t set up DKIM keys, verify that you own a domain via an authorized email domain.

• Set Up an Authorized Email Domain
  To verify your email-sending domain without DomainKeys Identified Mail (DKIM), set up an authorized email domain. For example, if your users’ email addresses are in the format name@example.com, set up an authorized email domain for example.com.
• Copy Authorized Email Domains into a Sandbox
  To avoid a second round of DNS verification, import your authorized email domains from production to a sandbox. In production, specify the authorized email domains to copy to a sandbox. Then, in a sandbox, import the available domains with one click.