DKIM lets you add a digital signature to outbound email messages in the message header. You should use DKIM in addition to SPF and DMARC to help prevent spoofers from sending messages that look like they are coming from your domain. Summary: This article describes how you use DomainKeys Identified Mail (DKIM) with Office 365 to ensure that destination email systems trust messages sent outbound from your custom domain. In the Edit signature box, type the text that you want to include in the. Type a name for the signature, and then click OK. On the Message tab, in the Include group, click Signature, and then click Signatures. Get a digital signature from a certificate authority or a Microsoft partner If you plan to exchange digitally-signed documents together with other people, and you want the recipients of your documents to be able to verify the authenticity of your digital signature, you can obtain a digital certificate from a reputable third-party certificate authority (CA). To create and use email signatures in Outlook Web App, see Create and add an email signature in Outlook Web. Important: If you have a Microsoft Office 365 account, and you use Outlook and Outlook on the web or Outlook on the web for business, you need to create a signature in each. You’ll have to add the signature manually to this one message.
