Sending emails from Microsoft managed email services like Outlook.com and Office 365 to our domain which has DNS hosted on Cloudflare has a terrible 8 hrs to 24 hrs delay. In some cases the mail is never received and a bounce email with the following error is received.
11/26/2021 2:53:45 AM - Server at abcde.com (0.0.0.0) returned '450 4.4.312 DNS query failed
Does Cloudflare block certain Microsoft email services? Why does this happen and is there anyway around it?
We have been experiencing this for a number of months and can’t seem to find a solution around it. Any help would be much appreciated. Thank you.