Spam Checking Policy
All our incoming mail is now checked against the Spamhaus DNSBL lists which contains a list of known machines, domains, addresses and servers sending spam emails.
You can read more details about this list at: http://www.spamhaus.org/zen/
If you are being told by an email sender that email they sent you is being bounced back to them, then it is HIGHLY likely that they, or their ISP, or their mailserver is on the mail blocklists - this is something that the *SENDER* of the mail should take up with their email provider, and not something that we can or will have any control over.