Windows 7 64bit, Outlook 2007 32bit client, FMPA 13.
I use the send mail script step, asking to send using client. The email goes to the Outbox, as expected. But once the email is sent, there is no copy in the Sent Items. When we send emails from within Outlook, the messages are copied to Sent Item. Why in the world is it not the case when sending from FileMaker ?
I do this regularly using Mail on a Mac, and the outgoing mail is put into my outbox, so perhaps it's a Windows/Outlook issue not FM. As a workaround you could try sending it to yourself as a CC. At least that would put it into your Outlook mail system.