Receiving tasks request from Exchange
From Zarafa wiki
Task requests from Microsoft Exchange are normally sent using normal html text to users outside the Exchange server. This means these mails will be delivered to Zarafa accounts as a normal email, and not as a task request without the 'Accept' and 'Decline' buttons. For this to work, Exchange needs to send the task request including the extra outlook information attachment. To force this, make sure Outlook is sending Rich Text Format to the addressee.
When typing the email address, follow these steps:
1. Click 'Assign Task' 2. In the 'To:' field, type the email address 3. Click the 'Check names' button, to get an underlined address 4. Double click the address to open the email address properties dialog 5. Select 'Send using Outlook Rich Text Format' in the 'Internet format' dropdown 6. Click OK
When using a contact:
1. Open the contact 2. Double click the underlined email address of the contact to open the email address properties dialog 3. Double click the address to open the email address properties dialog 4. Click OK, and 'Save & Close'
The contact can now be used in task requests.
Note: This must be done on the sender side, the person using Exchange.