The qf file lists all the recipients for a mail message. There can be one recipient or many. When sendmail creates the qf file, it lists each recipient address on an individual R line. The form of the R line in the qf file looks like this:

Rflags:addr

The R must begin the line. Only a single address can appear on each R line. There can be multiple R lines. Each is processed in turn.

If the colon is present and if the version of the qf file is greater than 0, the characters between the R and the colon are interpreted as flags that further define the nature of the address:

P

(primary) Addresses can undergo many transformations prior to delivery. When expanding aliases, for example, the address george might be transformed into two addresses via a ~/.forward file: george@here and george@there. In this instance, george is the primary address, and the aliases are secondary addresses. If aliasing yields only a single transformation, the single new address is considered primary. Addresses that are received via a RCPT SMTP command, or on the command line, are always considered primary, as are all other recipient addressees prior to aliasing.

N

(notify) Recipient addresses can lead to various kinds of notification based on the nature of the DSN NOTIFY extension to the RCPT SMTP command. That notification can be either NEVER or some combination of SUCCESS, FAILURE, or DELAY. Internally, sendmail uses the absence of the latter three to imply NEVER. This N flag simply says that the DSN NOTIFY extension appeared in the message. If the N is absent, but an S, F, or D is present, DSN information will not be propagated. Note that NOTIFY can also be specified by using the -N command-line switch (-N).

S, F, D

(success, failure, delay) The DSN NOTIFY extension to the RCPT SMTP command will specify either NEVER or some combination of SUCCESS, FAILURE, or DELAY. When any of these is specified, its first letter is used as a flag for the recipient address. SUCCESS means to notify the sender that final delivery succeeded. FAILURE is used to notify the sender that some step toward delivery failed fatally. DELAY lets the sender know that the message has been delayed but delivery will continue to be attempted.

A

If the address in the R line is the result of an alias expansion, this A flag is included to indicate that fact.

Each R line is fully processed as it is read. That is, the line is scanned for multiple addresses. Each address that is found is alias-expanded. Each resulting new address is processed by the canonify rule set 3 and the parse rule set 0 to resolve a delivery agent for each.