Running OS X Mojave 10.14
Default mail client (set in mail) is outlook 2016 (16.20)
Send mail script asks for permission for Filemaker to control outlook (permission is granted and shows up in system preferences)
However, on running a send mail script step to email client, outlook is brought into focus, but no email is created.
Tried on 16 and 17.0.3/4
This meets all of Filemakers minimum requirements for email sending.