Since Microsoft Dynamics GP 2013 R2 saw the introduction of a new Workflow module for approval of documents, almost every version of Dynamics GP since then has introduced new functionality to workflow; sometimes in the form of new approval types or integration with other modules such as Document Attachment.
This diagram shows the available workflow types, colour-coded by version introduced:
If you are looking to implement workflow, I have a book which can guide you though configuring the Microsoft Dynamics GP Workfow module from the basics of designing your workflow process, through building it and the ways that users can interact with the workflow for approvals.
The Workflow module is quite popular and becoming much more so with so many clients working in a distributed manner. There is one problem on the horizon and that is the retirement of TLS 1.0 and 1.1 which the Web Services for Microsoft Dynamics GP rely on. We are waiting for confirmation as to when a fix for this will be available, but I am expecting the fix to require an upgrade of Microsoft Dynamics GP which isn’t always quickly possible.
One of those products is PurchaseHQ which provides an Azure hosted web portal through which users can log on to do their purchasing series approvals. It fully integrates with the Workflow module in Microsoft Dynamics GP (blog and video) for document approvals (blog and video). The portal is quite a popular approach for organisations with a lot of approvals which need to be done as approvers have a web page they can logon to to see all of their approvals for all companies in one list, rather than receiving one email per approval.