SPF record or Sender Policy Framework is a TXT record that works as a security mechanism that prevents other people from sending emails on your behalf.
You can easily enable the SPF record on cPanel by going to Email Deliverability, located in the Email section:
Next, click on the Manage button for the domain you wish to enable the SPF record for:
If you want to set a default SPF record, scroll down to Suggested SPF Record and click on the Customize button:
Then scroll down to the Additional settings section and include the following two new entries by clicking on Add A new “+include” item:
spf.mx.hostinger.com
relay.mailchannels.net
Once done, scroll all the way down and click on Install a customized SPF record:
If you would like to add custom SPF records from your current email provider, you can do so by editing your domain's TXT records.
After SPF is enabled or added, a new TXT record will appear in your DNS Zone. After up to 24 hours, once propagation is completed, the SPF record will be fully operational.