Because spammers often masquerade as legitimate senders (claiming that their emails are coming from a real company or person).
Receivers will often see authentication as a way to verify if the sender is really who they say they are. This is especially important when using an email service provider as they may (or may not) be allowed to send on your domain’s behalf.
It is important to authenticate the email address you will be sending campaigns from. This will maximize the deliverability of your emails and ensure your emails will not be marked as spam.
HOW TO VALIDATE YOUR EMAIL ADDRESS:
There are four main protocols in use today:
- Sender ID
- Domain Keys
To validate your email address, go to Settings > Validate your email address
In Step 1 you will enter the email address that will appear as the sender email
(what will appear under "From" in the header of your email)
Step 2 will provide you with DNS setup instructions. There are three methods available:
Add a CNAME record to the DNS for the DKIM authentication - How to do it in cPanel?
If your panel does not accept "_", you will be provided with an alternate DKIM record
Add a TXT record for the DKIM authentication
When the authentication is complete, you will see a prompt letting you know. Keep in mind the process this process can take several hours, so check back if it doesn't work right away.