SPF 5.7.1

Hi all,

It seems we are also being hit with the below bouncebacks for any of our tennants on Office 365 sending to anyone who uses Symantec protection.

The bounceback we are receiving is as follows (for example):

This is a delivery failure notification message indicating that
an email you addressed to email address :
-- XXX.XXX@fco.gov.uk 

could not be delivered. The problem appears to be :
-- Recipient email server rejected the message

Additional information follows :
-- SPF (Sender Policy Framework) domain authentication
fail. Refer to the Troubleshooting page at
http://www.symanteccloud.com/troubleshooting for more 
information. (#5.7.1)

This condition occurred after 1 attempt(s) to deliver over
a period of 0 hour(s).

If you sent the email to multiple recipients, you will receive one
of these messages for each one which failed delivery,  otherwise
they have been sent.

Our SPF records for all 365 tennants are up to date as they should be. Any ideas on what we can do? This is starting to impact our organisation...