It looks like SShot has been IDed as a source of spam. 

5.1.0 - Unknown address error 550-'Connections from the host mx194.callplus.net.nz (202.180.66.194), originating from SenderBase Network Owner ID: 1565790, are being rejected due to a low SenderBase Reputation Score. See http://www.senderbase.org for more information or contact your IT support team.'

Has anyone else encountered the same issue? I am getting fed up having emailed rejected.

H.