This article maintains a list of known issues for the current release
Microsoft will discontinue support for TLS 1.0 and 1.1 on October 31 2018. This means that if you have not enabled TLS 1.2 you may experience connectivity issues to SharePoint 365 after October 31.
A pre-requisite of OnePlace Solutions products is .NET Framework. Older versions of OnePlace Solutions rely on .NET framework 4.5.2, and therefore will be impacted by this change.
OnePlaceMail 7.6 and older + Office 365, TLS version on-premises SharePoint
The following windows environment variable can be set for enabling detailed Outlook and VSTO (Visual Studio Tools for Office) error messages when loading VSTO add-ins.