Whitelisting of the mailserver

Modified on Mon, 07 Aug 2023 at 09:18 AM

Sometimes e-mails do not reach the customer. For example, we sometimes receive reports from customers that an e-mail allegedly sent to users with a, or a e-mail address is not received by the user. 

So far, we have been able to establish that these are mainly messages sent using a customer's e-mail address. If external mail servers (such as those of e.g. Microsoft, Google or of the recipient's company) perform a check to establish that it is not spam, the e-mail does get marked as spam. This is because mail server of the learning environment is on our server and our server is not part of the customer's network. As a result, the email is rejected and marked as "Email Spoofing" (impersonating someone else). 

So it is important to understand that this is not just monitoring that Microsoft is doing. The same can occur with your own internal mail servers if you try to send e-mail from our server to your internal employees. So it all depends on the checks performed by the receiving mail server.


So the following example scenario can lead to a refusal of the e-mail by the mail servers of e.g. Microsoft:

  • The e-mail from the LMS is sent on behalf of
  • The recipient is
  • The e-mail is sent and the Microsoft mail server catches it. Now the e-mail is traced to its source. In this case, it arrives at our server. Since our server is not known anywhere as a server of the domain "", the receiving server assumes something is wrong and rejects the e-mail.


To determine whether you are dealing with this phenomenon, you can do the following test:

  • Involve a user in the test who you know is experiencing this problem.
  • From your learning environment, send an e-mail on behalf of to this user.
  • Most likely, this e-mail will arrive.
  • Now send an e-mail in the same way from your normal address, e.g. >
  • Most likely this e-mail will not arrive.

If this is the case in your situation, you are probably dealing with the problem described here. 

Possible solution(s)

To get the e-mail to the addressee, it is necessary that the server where the e-mail comes from is recognised as a server from your own network. We currently have two solutions available for this.

  1. You have our mail server added to the Sender Policy Framework configuration of your domain (Sender Policy Framework (SPF) is an e-mail validation system specially devised for this purpose). Your IT department will need to assist you with this.
  2. We can deliver the e-mail directly to your mail server. To do so, the mail server must then allow this. This should also be done in consultation with your IT department. 

In addition, it is possible to have the e-mail sent with a DKIM (encryption signature). This is an extra step that, together with the SPF route, provides sufficient security to receiving mail servers that the e-mails are OK. For this, we will have to engage our hosting party; they can set this up together with your IT department.

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