This is a common issue as the Application certificate that has been created in MailStore and uploaded to Azure Portal will have expired. To resolve this you need to create a new certificate within MailStore and upload it to the mailstore registered APP in the Azure portal.
The steps to do this are..
- Open the MailStore Client, login as An Administrator and navigate to Administrative Tools > Users and Archives > Directory Services.
- You should already be using the Directory Services Type ‘Microsoft 365 ( Modern Authentication).
Under the Connection > Credentials section click on the three dots after the pull-down menu to open the Credentials manager. - Select and edit the Credentials you have previously created.
- Click on the small down arrow after the certificate section, and choose ‘Create Certificate’.
- Click on the small down arrow after the certificate section, choose ‘Download Certificate’ Name and save the certificate to a local folder.
- Choose OK to save the changes within the Credentials.
- Choose ‘Apply to apply these changes in the credential Manager and close it.
- Open the Azure Portal https://portal.azure.com and navigate to the App Registrations (Direct link https://portal.azure.com/#view/Microsoft_AAD_IAM/ActiveDirectoryMenuBlade/~/RegisteredApps)
- Select the MailStore application within the ‘All applications’ section.
- On the left hand menu select ‘Certificates & Secrets’.
- Click on ‘Upload certificate’.
- Select the file you previously saved and add a description and click add to add the certificate.
- Take note of the Expiry date, we recommend adding a calendar reminder before this date to repeat this process.
