Certificate authority (CA) A certificate authority is an entity similar to a notary public. It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired. Top of Page Digital signature assurances The following terms and definitions show what assurances are provided by digital signatures. Authenticity The signer is ...

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Signing your email messages with a digital ID helps to prove your identity and prevent message tampering.

A phishing email is an email that appears legitimate but is actually an attempt to get your personal information or steal your money. Some deceptive emails appear to be from a safe sender but, in fact, have a "spoofed" source address to fool you. Here are some ways to deal with phishing and spoofing scams in Outlook.com. Spoof intelligence in Exchange Online Protection helps prevent phishing ...

Send S/MIME or Microsoft Purview encrypted emails in Outlook using a work or school account with a qualified Microsoft 365 subscription.

Learn how to identify and open encrypted and protected emails no matter what email client you're using.

How to create or edit your Outlook signature for email messages. Include your signature, text, images, electronic business card, and logo.

Whether it’s a new job title (congratulations!) or a phone number change, make sure you keep your email message signature up-to-date. If you're using new Outlook, for more information about email signatures, or if you haven’t created one yet, see Add a signature to messages. Select File > Options > Mail > Signatures. Select the signature you want to edit, and then make your changes in the ...

Find out how to troubleshoot issues redeeming Xbox digital codes and gift cards.

The type of support Microsoft provides for consumers depends on the product you're calling about and if you have a product for home or for business use. It can also depend on if you want help for an issue with a service like OneDrive or Outlook.com, or help with Windows, but you don't have an existing Microsoft 365 subscription.