Add Email Headers

# This call sends an email to one recipient with a Reply-To address.
curl -s \
	-X POST \
	--user "$MJ_APIKEY_PUBLIC:$MJ_APIKEY_PRIVATE" \
	https://api.mailjet.com/v3/send \
	-H 'Content-Type: application/json' \
	-d '{
		"FromEmail":"pilot@mailjet.com",
		"FromName":"Mailjet Pilot",
		"Subject":"Your email flight plan!",
		"Text-part":"Dear passenger, welcome to Mailjet! May the delivery force be with you!",
		"Html-part":"<h3>Dear passenger, welcome to <a href=\"https://www.mailjet.com/\">Mailjet</a>!<br />May the delivery force be with you!",
		"Recipients":[{"Email":"passenger@mailjet.com"}],
		"Headers" : {"Reply-To":"copilot@mailjet.com"}
	}'