How to not get a fraud detection error at outlook

Question

I am currently making a html email for a big client. Visitors can enter their email in a Facebook app, and then they get a mail with instructions. In all mail clients I've checked I pass the spam protection because I've got a valid FROM and headers, I even set up SPF records.

But at outlook.com my mail doesn't get in the spam folder, but it does add a banner with:

Be careful. This sender is not approved by our controls for fraud detection.

I am using phpMailer to send my emails.

Is there anyway I don't get this error?

Answer 1

After a long search I found a working SPF record for outlook.com.

v=spf1 ip4:<server IP address> include:outlook.com ~all

This fixed all of my problems