Does the exchange connector need to be installed on all Mailbox server? If not, is installation on multiple Mailbox servers supported in order to drive HA?
If you review the Exchange connector install guide found here:
Nintex Workflow 2010: Exchange Connector Service Installation and Configuration Guide
Nintex Workflow 2013: Exchange Connector Service Installation and Configuration Guide
It specifies the following:
If your Exchange environment is implemented across multiple machines, the Exchange Connector Service should be installed on the machine running the Exchange Mailbox role.
As far as I know you setup one Exchange server for the Nintex environment to use. The Exchange Connector for SharePoint should be created on this Exchange server.
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