Securing the mails delivery

To secure your mail server and the delivery of your e-mails, we recommend that you use the following three protocols:

SPF

The Sender Policy Framework (SPF) allows to declare your mail server as authorized to originate mail for your domain(s).

To configure it, you have to add a single dns record to add:record:

Type: TXT
Host: @ (depending of your DNS provider, it can be your domain name example.com, a blank string, a @, etc.)
Value: v=spf1 include:_spf.hosterra.tech ~all

DKIM

DomainKeys Identified Mail (DKIM) is an e-mail authentication method designed to combat mail spoofing.

To configure it, you have to add two dns records. To get these two specific records, just access the Plesk interface of your server, then:

click, in the left side menu, on Mail;

click the Mail Settings tab and select the concerned domain;

check the Use DKIM spam protection system[…] at the bottom of the page

get the 2 dns records to add by clicking on How to configure external DNS.