Contact form emails ‘From’ address

Hi

I’m using Postman SMTP to send all my emails from WordPress and it works a treat, for all emails other than those from my Jetpack Contact form.

The email logs for the Contact form shows that the “From” address is always “wordpress@<my site url>” which means that my ISP is rejecting them as they do not authenticate.

Sample output:

From:	"Joe xxxxxxx" <wordpress@www.xxxxxxx.uk>
To:	stuart@xxxxxxx.uk
Reply-To:	"Joe xxxxxxx" <joe@example.com>
Date:	2017-03-09 15:14:34
Subject:	xxxxxxx Contact Form
Delivery-URI:	smtps:plain://xxxxxxx:465

I don’t see anywhere in Jetpack that I can configure this and the help text for the Contact form suggests that Jetpack should use Postman as the sender?!

Any idea what I can do?
Thanks
Stuart