Open Task Button does not come in Outlook

Question

I have a three level approval workflow in which each level an email is generated to the approve to approve or reject.
But suddenly the Open Task Button does not pop up in Outlook 2010 anymore can you tell me why?
Srinivasan Kidambi

Answer 1

had the same issue with External users not using Outlook. This is how I fixed it:
Open the task list that the workflow is using and connect it to Outlook. Then kick off a workflow to make a new task. Once the task is made open the task from Outlook. The bottom options (review, perform the specific req. for the task, and Open this task)
are now links. Hover your mouse over the link and you will see the address.
Now open SPD, connect to your site and open the work flow assc. to the doc lib.
Start editing the workflow and click the "Approval" link
Click "Change the behavior of a single task"
You are going to have to look for all the instances of "then e-mail task notification to "Current Task:Assigned to"
Open "Current Task:Assigned to"
Click where you want he link to go and hit the Hyperlink button
name the link whatever you want, then hit the string builder ("..." button)
Copy the link from the Task in Outlook into the string builder (if you use External addressing you can also hard code the External address).
At the very end of the link where is says ID=(then a number) delete the number and DO NOT put a space. Click the Add or Change Lookup button and use "Current Task: Approval" "ID" "As String" and click ok. Should like this:
Now this will not pop the form up, but it will send the user straight to the task form (might have to enter username and password) for the correct task. Remember to do this to all the "Current Task:Assigned to" in the workflow. It sounds like a chuck of
work but it does not really take thaty long on the OOTB Approval workflow.
Just wanted wanted to add my two cents.
Also check
http://social.technet.microsoft.com/Forums/en-US/417466a3-cdcb-4559-8453-9fff6da4aceb/getting-around-a-missing-open-this-task-button-in-a-nonoutlook-email?forum=sharepointcustomizationprevious
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