18. The ipliteral router
Author: The Exim Project. <https://www.exim.org/>
Description: Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
Keywords: exim,smtp,mta,email

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## Chapter 18 - The ipliteral router

This router has no private options. Unless it is being used purely for verification (see verify_only) a transport is required to be defined by the generic transport option. The router accepts the address if its domain part takes the form of an RFC 2822 domain literal. For example, the ipliteral router handles the address

    root@[192.168.1.1]

by setting up delivery to the host with that IP address. IPv4 domain literals consist of an IPv4 address enclosed in square brackets. IPv6 domain literals are similar, but the address is preceded by `ipv6:`. For example:

    postmaster@[ipv6:fe80::a00:20ff:fe86:a061.5678]

Exim allows `ipv4:` before IPv4 addresses, for consistency, and on the grounds that sooner or later somebody will try it.

If the IP address matches something in ignore_target_hosts, the router declines. If an IP literal turns out to refer to the local host, the generic self option determines what happens.

The RFCs require support for domain literals; however, their use is controversial in today’s Internet. If you want to use this router, you must also set the main configuration option allow_domain_literals. Otherwise, Exim will not recognize the domain literal syntax in addresses.

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