In addition to this blog, you can search the Nintex for SharePoint 2016 help for "Nintex Workflow Exchange Connector Service."

Action that uses Exchange

The following Nintex Workflow action uses the Nintex Workflow Exchange Connector Service to communicate with Exchange (2007, 2010, and 2013): 

• Provision User in Exchange (2016 | 2013 | 2010)

Setting up your environment to use Exchange

Setting up your environment to use Exchange for Nintex Workflow actions involves installing the Nintex Workflow Exchange Connector Service, adding root certificates to SharePoint, and ensuring that the intended user has access to the target calendars.

Installing the Nintex Workflow Exchange Connector Service

To install the Nintex Workflow Exchange Connector Service

1. Begin the process to export files from the installer file for Nintex Workflow by running the installer.
2. Progress through each page of the installer wizard until the export option is presented.
3. Select the export option.
4. When prompted for the destination folder, select the desktop.
   The installer exports files to the desktop (Workflow folder) and then exits.
5. On the desktop, open the Workflow folder, and then open the Supporting folder.
6. Review the installation guide provided for the Nintex Workflow Exchange Connector Service and follow its instructions.
   Note: For Exchange 2013 only, the application pool must be configured to use .NET framework version v4.

Adding root certificates to SharePoint

To add root certificates to SharePoint (Central Administration)

• In Central Administration, under General Security, click Manage trust. Refer to SharePoint documentation for further detail.

To add root certificates to SharePoint (Windows PowerShell)

• Use the following PowerShell cmdlet:
  foreach ($cert in (Get-ChildItem cert:LocalMachineRoot)) { if (!$cert.HasPrivateKey) {New-SPTrustedRootAuthority -Name $cert.Thumbprint -Certificate $cert } }

Ensuring user access to target calendars

To ensure user access to target calendars, do one of the following

• Ask the target user to provide the source user with write access to their calendar.
• Use Exchange Management Shell. Refer to Exchange documentation for further detail.

More information

The following errors may indicate the need to set up your environment to use Exchange.

• "The root of the certificate chain is not a trusted root authority" - if you see this message, add the root certificates to SharePoint following the instructions above.
• "Failed to invoke Microsoft Exchange web service. Error returned from server: Unable to connect to the remote server" - if you see this message, make sure your environment is set up to work with Exchange for Nintex Workflow actions.