+1 coinfor reading to the end
+1
Home / Glossary / S/MIME
Glossary · Protocol

S/MIME

Secure/Multipurpose Internet Mail Extensions

In plain language

A way to sign and lock email so the recipient knows it came from you and only they can read it.

The metaphor

Like a letter sealed in a signed envelope: the signature proves who sent it and only the addressee can open it.

Going deeper

How it works

  • Each person has a digital certificate.
  • The sender signs the message and, if needed, scrambles it for the recipient's certificate.
  • Both sides must have it set up.
  • It is used where email carries very sensitive material.
In practice
  • A law firm exchanges signed contracts with a partner firm.
  • A clinic sends test results to another clinic in a locked message.
  • A company is asked by a client to sign its emails.

A question owners ask

Do I need it?

Most small offices do fine with a secure portal or a protected attachment link. Use it if a client or contract requires it.

Related terms
AHAuthentication HeaderARPAddress Resolution ProtocolBGPBorder Gateway ProtocolCCMPCounter Mode/CBC-MAC ProtocolCHAPChallenge Handshake Authentication ProtocolCRCCyclical Redundancy CheckEAPExtensible Authentication ProtocolESPEncapsulated Security Payload

Something here sounds like your problem?

Every WILDCARD card exists to solve one named problem. Find yours.

Pick your problem →