sendmail, 4th Edition

$u

Address part of a delivery agent triple All versions

The parse rule set 0 (The parse Rule Set 0 on page 696) is used to resolve the recipient address into a triple: the delivery agent (with $#), the host part of the address (with $@), and the recipient’s address (with $:). The recipient’s address is then processed by rule set 2 (the generic rule set for all recipient addresses), then by the rule set indicated by the R= equate of the delivery agent (the custom recipient address processing), and finally by the final rule set 4 (post-processing for all addresses).

If the delivery agent has the F=A flag set (F=A on page 767), that rewritten recipient’s address is looked up in the aliases file and replaced with its alias if one exists. If it is not replaced and if the F=5 flag (F=5 on page 764) is set, the address is rewritten by the localaddr rule set 5 to possibly pick a new delivery agent and repeat this process.^[323]

After aliasing, the rewritten recipient’s address is then assigned to $u. If the delivery agent’s F=w flag (F=w on page 781) is set,^[324] the value of $u is then used to look up information about that user with the method defined by the MailboxDatabase option (MailboxDatabase on page 1042).^[325] The user’s home directory is made the value of $z, which in turn is used to access the user’s ~/.forward and dead.letter files.

For all delivery agents, the final value of $u can be used as a component of the delivery agent’s A= equate (A= on page 738). For example:

A=uux - $h!rmail ...