What does a digitally signed e-mail message validate?

A digitally signed e-mail message primarily validates the sender. When a sender signs an email digitally, they are using a cryptographic mechanism that associates their identity with the message. This signature ensures that the email was indeed sent by the claimed sender and not altered in transit. The recipient can verify the signature using the sender's public key, which enables trust in the authenticity of the communication.

The act of signing does not validate the recipient; it focuses on confirming the identity of the sender. Additionally, while a digitally signed email might be encrypted as well, signing and encryption are separate processes. A digitally signed message does not guarantee that the email is virus-free; it merely assures that the content has not been tampered with since it was signed. Therefore, the correct understanding is that a digital signature provides authentication of the sender's identity.