GreenArrow Email Software Documentation

Legacy Recursive DNS Server

Legacy Recursive DNS Server on localhost

GreenArrow can provide a recursive DNS server that listens on This server is disabled by default on new installs and can be turned off and on with the dns_cache_service_run configuration parameter.

We recommend not using this service and only provide limited support for it. See below.

History & Support Status

Formerly, GreenArrow required that its own recursive DNS server run on and that /etc/resolv.conf be configured to query it.

GreenArrow now only requires that a working recursive DNS server be configured in /etc/resolv.conf. Configuring this is the responsibility of the system administrator.

GreenArrow instances that were installed when this DNS server was required and enabled by default continue to have it enabled until it is replaced and disabled by the system administrator of the GreenArrow server.

New GreenArrow instances do not enable this DNS service.

We no longer recommend using GreenArrow’s recursive DNS service.


When disabling GreenArrow’s Legacy Recursive DNS Server on localhost, you MUST provide a new recursive DNS server to the operating system.

There are two ways do this:

  1. Run a different recursive DNS server that binds to, or
  2. Update /etc/resolv.conf to point to a different location for a new recursive DNS server.

If you update the DNS servers configured in /etc/resolv.conf then you must:

  1. Restart GreenArrow to cause /etc/resolv.conf to be re-read by GreenArrow, and
  2. Restart any other long-running processes that do not automatically re-read /etc/resolv.conf such as Apache. The fact that the /etc/resolv.conf man page on most Linux distributions does not mention this is something we consider a bug.

You may restart all GreenArrow services by running this command:

systemctl restart greenarrow.service

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