Issues sending email to Outlook.com

We are seeing some email sent to Outlook, Hotmail, Live and MSN rejected with the following bounce-back error message:

550 5.7.1 Message rejected: Message lacks SPF/DKIM/DMARC Auth Records

Outlook.com appear to have started to reject email from domains without a DMARC record, even if they have SPF and/or DKIM in place.

Do I need to take any action?

Domains using our name servers: These are not affected, we automatically add a DMARC record for you.

Domains using external name servers: These need a DMARC record adding if they don’t have one.

What to do if your domains use external name servers:

If your domains use external name servers, double check a DNS record called _dmarc exists. If it doesn’t exist, add the following DNS record to set one up:

Name: _dmarc
Type: TXT
Value: v=DMARC1; p=none;

If you are still having issues, please contact support with a copy of the bounce-back error message you receive.