As a part of the STARTTLS form of authentication and encryption, certificates are usually exchanged. This ${cert_subject} macro is assigned the distinguished name (the DN) of the certificate presented by the other side. That value might look like this:


See Section for an illustration of one use for ${cert_subject}. See Section 21.6.2 to find how and why the value in this macro undergoes special translation.

${cert_subject} is transient. If defined in the configuration file or in the command line, that definition can be ignored by sendmail. Note that a $& prefix is necessary when you reference this macro in rules (that is, use $&{cert_subject}, not ${cert_subject}).

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