Correct, it is not possible to drill back from a workflow email notification to the document when using Web Client due to a limitation of HTML which is what the Web Client application uses in the browser window.
The rich client of Dynamics GP works fine with the drill back functionality, so that is an option.
Otherwise, for Web Client Only users, each workflow has a setup of navigation lists that will show this same type of information. For example, for the Purchase Order Approval workflow, there are three lists under Purchasing:
--Purchase Orders > this will show all purchase orders regardless of status
--Purchase Orders Not Submitted > this will show purchase orders that are not currently pending approval or action through Workflow
--Purchase Orders Pending Approval > this will show the purchase orders that are currently pending action through Workflow
Each workflow type has the same set of three lists available, which users can then use to select one of the workflows in the list and see information about it below as well as double-click on it in the list to bring up an inquiry window with the information in it.
For example, when I have a pending PO for approval in Workflow, I can go under Purchasing and click the Purchase Orders Pending Approval list and see the POs pending approval, not necessarily for myself.
From this list, I can see information about it below the list of pending POs, as well as double-click on a specific PO which pulls up the Purchase Order Inquiry Zoom window with that PO selected, in order to view the information.
So, by this, Web Client Only users would still be able to view information about the workflow they are about to approve, similar to what the Edit/View link in the email notifications would be doing. Either way they would need to be logged into the same company database the workflow was submitted in, in Web Client.
Let me know if you have any further related questions.
Thanks