Common errors

Here you can find some common errors in M365 context. Also have a look at the general M365 documentation for the configuration.

Incorrect client ID

Error message: AADSTS00016: Application with identifier ‘xxxxxxxx’ was not found in the directory ‘MSFT’. This can happen if the application has not been installed by the administrator of the tenant or consented to by any user in the tenant. You may have sent your authentication request to the wrong tenant.

Error message

In this case, please compare whether the client ID created in Zammad matches that in Azure for the Azure App.

The Client ID can be found in Zammad under Settings > Channels > Microsoft 365 > App Configuration. See here how to find the client ID in Azure and where to copy it to in Zammad.

Wrong or expired client secret

Error message: 500: We’re sorry, but something went wrong.

Error message

This error occurs when the client uses an incorrect or expired client secret.


Important notice: We never ask the client for the client secret as this can potentially be a security risk. We ask the customer to create a new client secret and copy the value and not the ID to Zammad.

See here for more information.

Wrong tenant

Error message: AADSTS0023: Specified tenant identifier ‘xxxxxxxx’ is neither a valid DNS name, nor a valid external domain.

Error message

If a wrong tenant is used in Zammad or the email account is not a member of the tenant created in Zammad, this error message occurs.

In this case, please check if the tenant is entered correctly in Zammad, or remove the tenant completely.


Important notice: Once the tenant is completely removed, all email accounts can be created in Zammad regardless of which tenant the email account is a member of.

Missing permissions for the Azure user

Error message: Can’t use Channel:Driver::SMTPAuthentificationError:Net::SMTPAuthentificationError

Error message

Error message in the M365 channel settings


Error message

Error message in the ticket

This error occurs when the admin wants to create an email account in Zammad whose user does not have permission for SMTP authentication to the mail server. Please check the following two most common problems in this case.

Private email account

If it is a private email account, the admin must grant the SMTP authentication permission to the user of the inbox. The permission is provided at

Add the SMTP authentication permission under Users > Active Users > click on the User > Email > Manage Email Apps.

Error message

Shared inbox

If it is a shared inbox, you can try to enable the SMTP Authentication (SmtpClientAuthenticationDisabled) in the Azure shell. This isn’t a Zammad problem, so we can only help to a limited extent here.

To enable the SMTP Authentication, use the following commands:

If not installed:

Import-Module ExchangeOnlineManagement

Log in to Exchange using Powershell:


Switching on the SMTP authentication for a mailbox - also possible with a shared mailbox:

Set-CASMailbox -Identity -SmtpClientAuthenticationDisabled $false