${if_addr_out}
The IP address of the send interface V8.12 and later
The sendmail program can send
SMTP email over one or more network interfaces,
where each interface can have one or more addresses
associated with it. When
sendmail sends a network
email message, it begins by connecting to a host on
the network. Once that connection has been made
(once the other site accepts the connection),
sendmail records the address
associated with the interface over which it made
that outbound connection in the ${if_addr_out}
macro.
If the connection uses an interface with an IPv4 address, that IP address is stored as, for example:
123.45.67.8
If the connection uses an interface with an IPv6
address, the address stored is prefixed with a
literal IPv6
:.
For example:
IPv6:3ffe:8050:201:1860:42::1
If the connection uses the loopback
interface, the value stored in
${if_addr_out}
is 127.0.0.1
for
IPv4
, and
IPv6:::1
for
IPv6
.
${if_addr_out}
is
available for use in rule sets, and can be useful
for rejecting spam or restricting connections to
particular addresses. Note that a $&
prefix is
necessary when you reference this macro in rules
(that is, use $&{if_addr_out}
, not ${if_addr_out}
).
${if_addr_out}
is
transient. If it is defined in the configuration
file or in the command line, that definition can be
ignored by sendmail.
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