sendmail, 4th Edition

$@

Specify host in delivery agent “triple” RHS delivery agent operator

The parse rule set 0 selects a delivery agent that can handle the address specified in the workspace. The form for selecting a delivery agent looks like this:

 LHS...  $#delivery_agent $@ host $: address

Three pieces of information are necessary to select a delivery agent. The $# specifies the name of the delivery agent. The $@ specifies the host part of the address (for [e-mail], the host part would be wash.dc.gov), and the $: specifies the user part of the address (the gw) for local delivery and the whole address (the [e-mail]) for SMTP delivery.

The use of $@ to specify the host can follow only the $# prefix part of the RHS. Note that $@ has a different use when the delivery agent is named error (see $@ on page 674).

The use of $@ to specify the host part of a delivery agent triple is described in detail in The parse Rule Set 0 on page 696. See also The use of $h in A=TCP on page 739 for how to use this $@ to specify the port to which sendmail should connect.