Send digitally signed messages as clear text if you want to make sure that your digitally signed messages can be opened by all recipients, even if they do not have an S/MIME mail application and can't verify the certificate.

A digital signature is an electronic, encrypted, stamp of authentication on digital information such as email messages, macros, or electronic documents. A signature confirms that the information originated from the signer and has not been altered.

From the Insert section of the ribbon, select Signature > Signatures. Select New, type a name for the signature, and select OK. Under Edit signature, type your signature and format it the way you like. Select OK and close the email. Select New Email to see the signature you created.

This article explains how you can get or create a digital signature for use in Office documents. To learn more about how to use them in Office documents, see Add or remove a digital signature in Office files.

The Signature Details dialog box displays certificate information such as the signer’s name in the Signing as box, and who issued the certificate. Open the file that contains the certificate you want to view.

If you don't see the Sign Message button, you might not have a digital ID configured to digitally sign messages, and you need to do the following to install a digital signature.

If a digital signature isn't valid, there can be many causes. For example, the sender's certificate may have expired, it may have been revoked by the certificate authority (CA), or the server that verifies the certificate might be unavailable.

To create an e-sign request, you’ll need to sign into your account with an available e-signature provider such as Adobe Sign or DocuSign. If you don't have account, it's easy to start a free trial or create an account.

Signatures can contain text, links, and pictures; for example, you can create a signature for a business email that includes your name, job title, phone number, and company logo.

If a digital signature isn't valid, there can be many causes. For example, the sender's certificate may have expired, it may have been revoked by the certificate authority (CA), or the server that verifies the certificate might be unavailable.