What Are DMARC, DKIM, and SPF?

I used to set up DMARC, DKIM, and SPF on my DNS management area for my domain but to be honest I don't really understand what they are? can anyone explain me?

In long form:

Domain Keys Identified Message (DKIM)
Domain-based Message Authentication, Reporting & Conformance (DMARC)
Sender Policy Framework (SPF)

They are intended as a means to prevent spammers spoofing their sender address to bypass other mail protection measures, or simply pretend to be another person. This is done by the above three mechanisms assigning authorisation keys, based around valid DNS, which means your DNS needs to have master keys... and for this to happen your domain registrar needs to have that on in their delegation... so if you don't have it working don't worry you arent alone - a recent stat from APNIC said the vast majority of such keys were not set up correctly... so even if you turned them on, they maybe werent working anyway...

Hello, Greetings.

DMARC : Publishing a DMARC record protects your brand by preventing unauthenticated parties from sending mail from your domain.
DMARC policy can tell a receiving server whether or not to accept an email from a particular sender.

DKIM : It works by associating outgoing email with a domain via a digital signature.
The receiving mail server will use a corresponding public key (the TXT record) to decode the signature and verify its authenticity.
Note : Over time, using DKIM can raise the reputation of associated addresses and subsequently improve deliverability.

SPF : The TXT record specifies a list of authorised host names/IP addresses that mail can originate from for a given domain name.
Example : v=spf1 a mx ip4:xxx.xxx.xxx.xxx -all

Regards

SPF (Sender Policy Framework) is a DNS text entry which shows a list of servers that should be considered allowed to send mail for a specific domain.
DKIM (DomainKeys Identified Mail) should be instead considered a method to verify that the messages’ content are trustworthy, meaning that they weren’t changed from the moment the message left the initial mail server

Hello,

I just wanted to add on to what others have said. Adding these records can reduce the number of emails sent from your accounts or server that end up in spam folders.

If you are using WHM you can also find out if you have configured any wrong or if they appear to be missing by going to "Email Deliverability" tab.

Hope that helps!