This mail is unauthenticated

[king1]

I think this is because you are sending off your own domain based email and there is no configured SPF record  or domain key setup  in the DNS records - google changed stuff there end (ie the "sender must authenticate with at least one of SPF or DKIM" bit} a while back to require one or the other from senders to gmail.  

You need to get your hosting provider to add an SPF/DKIM records - i've had a few business clients caught out by this