Sender Policy Framework (SPF) is a simple email-validation system to detect mail spoofing from forged "From" addresses.
The framework verifies that the sending host is authorized to send mails from the domain in the 'From' field of the mail.
You add SPF records to your domain name system (DNS) to notify your recipients of the hosts which are allowed to send emails from your domain.
An SPF record contains the IP addresses of authorized hosts in the form of a specially formatted TXT record.
Adding an SPF record to your DNS can overcome situations where a recipient mail server rejects mails from Service Desk to your end-users.
This article explains how to add SPF records if you are using Outlook email setup for your domain.
Add an SPF record
Go to the DNS management page of your domain.
Add a new DNS record with the values as follows:
Type = “TXT”
Hostname / Host / Name = Your domain name. Type "@" to map the record directly to your domain name, or enter the subdomain of your host name (labeled host), such as www or ftp.
TXT value = 'v=spf1 ip4:34.251.73.164 ip4:23.236.135.67 include:spf.protection.outlook.com -all'
TTL: Select how long the server should cache the information
Save the record.
See the reference manual of your hosting / DNS service provider if you need help with creating a new DNS record for your domain.