An email from this sender could not be delivered to your mailbox as it has failed DKIM verification. To comply with government security standards the ATO cannot accept emails that fail DKIM integrity checks because the email cannot be verified as genuine.
Currently there is an issue causing emails from organisations using Office 365 to fail DKIM verification.
Office 365 has implemented its own DKIM features and customers must ensure that outbound DKIM is correctly configured for their domain (DNS) and namespace (Office 356 Administration).
How to enable DKIM on 365
You will need to enable DKIM outbound DNS Verification on either 365
These need to point to
Your onmicrosoftalias is the domain GUID and can be retrieved from the MX record for your domain
You then need to enable
View Powershell :
New-DkimSigningConfig –DomainName domain.com –Enabled $true
Or through GUI :
If you send out via another provider e.g. a spam filter you will need to check the method on the spam filter of enabling this