As a part your email set you will need to have an SPF (sender permission) record created on your domain’s DNS file.
The Cloud provider like Microsoft will provide the instructions to do this but they do assume you have no external email senders like Courier Navigator.
There is a very simple addition to the file that allows Courier Navigator to send emails on your behalf without being caught by the recipients Spam filter.
In addition to the record supplied by the Cloud provider the Coda Commerce Network (83.245.109.0/24) will need to be included.
This can be done by whoever administers your domain DNS records.
If you want to check that your Navigator system is allowed to send emails please try this online tool and look for the 83.245.109.0/24 in the result.
Example of a domain with an SPF record not including Coda Commerce.
Example of a correctly setup Office365 record:
The first example is setup in a way that it is up to the recipients mail server, whether the email sent by Courier Navigator will be delivered.
So, it is possible that some emails will be delivered and some not which can create confusion.