Plesk
supports a number of anti-spam solutions for validation of mail
messages identity:
	- 
	DKIM
	(DomainKeys
	Identified Mail) is a method used to associate a domain name
	identity with an outgoing message and to validate a domain name
	identity associated with an incoming message through cryptographic
	authentication.
- 
	SPF
	(Sender
	Policy Framework) is a method used to prevent sender address
	forgery, i.e. using fake sender addresses. It allows mail server to
	check that incoming mail from a domain comes from a host authorized
	by that domain’s administrator. In addition, Plesk uses SRS
	(Sender
	Rewriting Scheme), so that forwarded messages can pass SPF checking.
- 
DMARC
	(Domain-based
	Message Authentication, Reporting and Conformance) is a technology
	to extend the capabilities of the SPF and DKIM methods. The DMARC
	policy defines how the receiver should treat email messages
	depending on the results of DKIM and SPF checking.
 
Enabling
DKIM Email Signing for Domains:
To
enable DKIM signing of outgoing email, go to 
Websites
& Domains >
Mail
Settings of
a domain, select the 
Use
DKIM spam protection system to sign outgoing email messages checkbox
and click 
OK.
If
you have activated DKIM for a domain, Plesk adds the following two
records to the DNS zone of the domain (
example.comstands
for your domain name):
	- 
	default._domainkey.example.com
    -
	contains the public part of the generated key.
 
- 
	_ domainkey.example.com
    -
	contains the DKIM policy. You can edit this policy.
 
In
addition to DKIM, Plesk supports SPF
and
DMARC
policies
for outgoing mail. 
You
can change the SPF and DMARC policies for your domain in the domain’s
DNS settings.
To
set up DMARC or SPF policy for your domain:
Go
to 
Websites
& Domains >
navigate to the domain > 
DNS
Settings and
edit the DNS records related to SPF or DMARC. For example, this
record contains the default DMARC policy:
_dmarc.domain.    TXT    v=DMARC1; p=
none