This might have something to do with Google.
Although I have this pluginactivated and set, I cannot send to gmail addresses as Google bounces it because invalid FROM address.
This from my server mail.log (while plugin activated and set)>
Dec 13 02:56:37 loft7376 postfix/smtp[1939]: CD7D137409D0: to=<[email protected]>, relay=gmail-smtp-in.l.google.com[74.125.136.26]:25, delay=0.36, delays=0.25/0.01/0.08/0.02, dsn=5.1.2, status=bounced (host gmail-smtp-in.l.google.com[74.125.136.26] said: 553 5.1.2 The address specified is not a valid RFC-5321 address. z133si15707954wmc.82 – gsmtp (in reply to MAIL FROM command