It installed successfully but its not working. Currently using on MAC OS High Sierra.

That's a very old version of our Email plug-in. High Sierra made changes that broke our old plug-ins. We've updated to accommodate for High Sierra; you need 3.06 or later (current version is 3.08).

@Jesse Barnum So it only affects High Sierra MAC OSX correct? How about Windows using Filemaker 16?

I would still recommend upgrading; I don't remember all the things that have been fixed since then but the list is long. With that said, I don't know of a reason offhand why it wouldn't work on Windows.

If only it would still work with 16.  3.08 is just a nightmare, errors, fails to load, gone were the days aof a nice stable solution

Have you contacted our support team at [email protected]? We have quite a few people using our plug-in with no problems, if there's something specific in your case causing a problem I'd like to get the log files so that we can fix it.