From 6aaa85b1a2c73ee7fd08c3f811cc79d48f8f3f7f Mon Sep 17 00:00:00 2001 From: Michael Wyraz Date: Fri, 15 Nov 2019 19:47:55 +0100 Subject: [PATCH] Document reverse DNS setup recommendations --- docs/dns.rst | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/docs/dns.rst b/docs/dns.rst index 027ce4fc..38ebd16c 100644 --- a/docs/dns.rst +++ b/docs/dns.rst @@ -49,6 +49,23 @@ And for another domain, ``myotherdomain.com`` for example: Note that both point to the same mail server hostname, which is unique to your server. +Reverse DNS entries +------------------- + +For a mail system, it's higly recommended to set up reverse DNS as well. That means, if your hostname +``mail.mydomain.com`` resolves to ``a.b.c.d``, the IP ``a.b.c.d`` should also resolve back to the same hostname. + +You can verify this with + +.. code-block:: bash + + nslookup a.b.c.d + +Reverse DNS must be set up by the "owner" of the IP address which is usually your hosting provider. You can look it up with ``whois a.b.c.d`` in most cases. + +With incorrect reverse DNS setup, most mail systems will reject you emails as spam. + + DKIM/SPF & DMARC Entries ------------------------