If you can not log in into your email account, please delete it and create it again after 2 hours.
A manual to create the account can be found here.
To delete your email account, please proceed as follows:
Choose the affected plan in the left menu item named “contracts”
Select the item " Email Accounts" in the following overview
Delete the affected email account via the orange "Delete" button
If the problem after another 24 hours still persists, please contact our support in writing