As the end comes nearer we've noticed our Workflow email server is still sending messages using TLS 1.0.  All products are version 10.4.2 and forms is successfully emailing using TLS 1.2, its just the Workflow server that isn't sending properly.  I've editted the registry entries to disable default negotiation of TLS 1.0 and have recreated our email server inside WF with recommended MS settings.  

Hopefully someone else has fixed this!