[done] UPN conversion for functional logins + guest logins March 12, 2026, 8 a.m. to 12 p.m.

On March 12, 2026, from 8:00 a.m. to 12:00 p.m., we updated the User Principal Name (UPN) of the functional or guest login you use to match its primary email address.

You can use this address to log in to your functional mailbox in your email program. With this change, we are adapting the login name to common Microsoft standards.

As a rule, you can continue working without restrictions. In individual cases, the following effects may occur:

• Outlook prompts you to log in again: Please use the primary email address of the function login to log in. If the login name cannot be edited, select “Log in with another user account.”
• Outlook signature is missing: Open a sent email, select and copy the signature, then paste it under ‘New Email’ -> ‘Signature’ -> ‘Signatures’ -> ‘New’, and specify at the bottom when it should be used. Confirm by clicking ‘OK’.
• Thunderbird requires you to log in again: If you are unable to enter your password successfully, cancel the process. In the account settings, change the username in the server settings to the primary email address of the functional login.
• Mobile email clients: Please check whether email retrieval continues to function correctly after the changeover. If necessary, adjust the user name in the settings to match the primary email address of the functional login.
  Notes:
• Public Exchange folders will be updated.