Gmail SPF Checks/Failures
Recently, Google have started enforcing the SPF record checks on domain names sending their clients emails, which may have caused some sent emails to be rejected.
The SPF record helps stop spoofed emails by confirming (through a DNS (TXT) record) that the server that has been used to send an email is one that is authorised to send messages on behalf of that domain.
In order to resolve the bounceback, you need to add a TXT DNS record to your domain name, if you are unsure how to add a DNS record, please review the following guide first: Managing DNS using cPanel Zone Editor
Once you have familiarised yourself with the DNS editor, please review the required TXT/SPF record below:
v=spf1 +mx +a include:relay.k.io +ip4:18.104.22.168 ~all
The IP4 entry should be the IP of your server, which you can find on the right hand sidebar of any of your cPanel accounts under the 'Shared IP' address heading.
For example, if you are on the hubble.krystal.co.uk server, the IP for the entry would be 22.214.171.124 and therefore, your SPF record would look like so:
v=spf1 +mx +a include:relay.k.io +ip4:126.96.36.199 ~all
Once the record has been added, it may take up to 24 hours for the DNS to propagate after which time you should no longer receive bouncebacks from Gmail