Hi Ben1974,
Thanks for Jesper Stahle’s information.
To solve the issue , I would like to confirm with you:
- You said “I have been instructed to 'add Email-OD.com to your SPF record that might fix the issue'”. Can you provide some screen shots here?
- What is your mail service deployment? Did you only use Office 365 service to send email ?
The SPF record that is needed for Office 365 service. Just add that TXT record. No need to follow the that the DNS hosting provider’s instructions
Thanks,
Jason Jiang