Exchange Online no longer supports use of TLS1.0 and TLS1.1 in the service as of October 2020. This change is due to security and compliance requirements for our service. While no longer supported, Microsoft servers still allow clients to use those older versions of TLS when connecting to the SMTP AUTH endpoint (smtp.office365.com).
To enable the use of TLS 1.0 and TLS 1.1 a couple of commands have to be run in Windows PowerShell (This process will require Administrator rights). You can launch it by pressing the following key combination "Windows key" + "X"
Installing the Modules
Once in PowerShell you will you have to execute the following commands in order to set everything up for use.
(When the module has been installed you will have to close and re-open the PowerShell using the same method as before in order to proceed.)
Enabling TLS 1.0 and TLS 1.1
If everything has been installed correctly you will then be able to connect to your account via the PowerShell (The "<UPN>" needs to be replaced with the Email Address of the account that you use in Microsoft Office).
This command will open a window in which you will have to type in the password that you use to log into your Microsoft Office.
Once you have successfully signed into your Microsoft Office account type the following command in PowerShell to enable Legacy TLS Clients (TLS 1.0 and TLS 1.1).
You can check if this has been done correctly by running this command (The result should say "True").
Testing
If everything has been done correctly you should now be able to use the SMTP.OFFICE365.COM email system inside of the P11D Organiser.
You can test that by going into the Email Configuration screen and pressing the "Send Test Email" button once you typed in your username and password.
