How to configure your server to send Email properly?


An article that groups the configuration steps needed to get a domain started with email sending and receiving.


This article makes the assumption that you have already installed a basic SMTP server installation such as PostFix.


Email security


email authentication is based:

  • DKIM: the email is signed and the signature can be verified with a DNS entry that contains the public key. When recipients receive your emails, their spam filters automatically query the domain to see if those signatures are not forged.
  • SPF: a dns record that defines which server(s) may send an email in your name.

It's used against spoofing, phishing or impersonation.



Configuring the reverse IP is part of the authentication.

Reverse DNS lookup or reverse DNS resolution (rDNS) is the determination of a domain name that is associated with a given IP address. Some companies such as AOL will reject any message sent from a server without rDNS, so you must ensure that you have one. You cannot associate more than one domain name with a single IP address.

The server does not have a Fully Qualified Domain Name (FQDN) and a PTR record

You may want to change your pointer (PTR type) DNS record and the host name of your server to the same value.

  • A
  • Reverse


Domain-based Message Authentication, Reporting & Conformance (DMARC) specifies how your domain handles suspicious emails.


Email - Encryption / Protection (S/MIME)


Microsoft server (Outlook, etc.) implements a white list policy where you can declare your server: For any problem, see New support request


The IP address of your sender server should not be blacklisted.

If a server shows bad email behavior (such as spam, spoofing, ddos), the server can be blacklisted.

Hosts are often blacklisted with spam filters, including known hosts such as HostGator or Blue Host.

See spam score

Email address

Use an email address from the same domain as your website in order to improve the spam score. Example:


When you are done with the configuration of your server and domain, you can validate it. See Email - How to test if your server email configuration was done correctly ?

Postmaster Tool

  • Gmail - Create an account at Postmaster Tools - You can use Postmaster Tools to track data on large volumes of emails sent and find data about your sending domain. You can view different dashboards to understand details like Gmail delivery errors, spam reports, feedback loop, and more.

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