All envelope addresses (sender and recipient) are passed through the parse rule set 0 so that a delivery agent can be selected. Upon receipt of the RCPT TO: address, a delivery agent is selected by the RHS of the parse rule set 0, which defines a triple that contains three pieces of information for that address: $# delivery_agent $@ host $:address The $ : portion of the triple contains the address part of the information with any commentary removed. For example: user@your.domain Once that address is determined for the $ : part of the delivery agent triple, it is copied to this ${rcpt_addr} macro. ${rcpt_addr} is transient. If it is 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 $&{rcpt_addr} , not ${rcpt_addr} ). |