There is no working preview or test-send button on the System Emails page in the current version - there is a preview modal in the page's code, but it is wrapped in a condition that is always false, so it never appears, and the endpoint behind it stops with an internal error before it can return anything. Practical ways to test instead:

1. Trigger it yourself - register a test customer, place a small test order, or request a password reset with your own address, then check your inbox.
2. Check the Email Log - Marketing > Email Log lists every email sent, its recipient, subject, status and whether it was opened, so you can confirm it went out even if it landed in spam.
3. Redirect all mail while testing - Sprwt support can set an internal System Email - Redirect To address (there is no toggle for this in the Client Config screens you see); while it is set, every email is delivered to that address instead of the customer, with (TO:original@address) prefixed to the subject and the original recipient recorded in the log. Remember to have it cleared afterwards.