${auth_authen}, ${auth_type}, ${auth_author}

Holds the client's authentication credentials, the mechanism used for authentication, and the authorization identity—the AUTH= parameter, if supplied.

${client_resolve}

Holds the result of the resolve call for ${client_name}: OK, FAIL, FORGED, or TEMP.

${deliveryMode}

Specifies the current delivery mode sendmail is using, instead of the value of the DeliveryMode option.

${dsn_notify}, ${dsn_envid}, ${dsn_ret}

Holds the corresponding DSN parameter values. 

${if_addr}

Provides the interface's address for the incoming connection if the interface does not belong to the loopback net. Is especially useful for virtual hosting. 

${if_name}

Provides the interface's host name for the incoming connection and is especially useful for virtual hosting.  

${load_avg}

Checks and reports the current average number of jobs in the run queue. 

${msg_size}

Holds the value of the message size (SIZE=parameter) in an ESMTP dialogue before the message has been collected. Thereafter, the macro holds the message size as computed by sendmail and is used in check_compat.

${ntries}

Holds the number of delivery attempts. 

${rcpt_mailer}, ${rcpt_host}, ${rcpt_addr}, ${mail_mailer}, ${mail_host}, ${mail_addr}

Holds the results of parsing the RCPT and MAIL arguments—that is, the resolved RHS triplet from the mail delivery agent ($#mailer), the host ($@host), and the user ($:addr).