# Email Authentication

Technical standards to help ISPs and other receivers validate the identity of an email sender.

Email authentication refers to technical standards that help ISPs and other receivers validate the identity of an email sender. There are three authentication standards in use: [SPF](/docs/sendgrid/glossary/spf/) developed by AOL, [Sender ID](/docs/sendgrid/glossary/sender-id/) developed by Microsoft and [DKIM](/docs/sendgrid/glossary/dkim/) developed by Yahoo!.