Yep, this is probably the explanation. ORBS lists PsiNet as an open relay, so sometimes it is impossible for us to contact a client.

I'm not a fan of the ORBS system - it's a good idea, but to summarily reject all email from PsiNet UK (a commercial ISP), for example, excludes a significant number of businesses here. They even exclude relay.demon.co.uk which is used by about a hundred thousand UK internet users.

In fact neither of these relays is open - but some of their clients run their own open relays, which ORBS picks up on. We think this is unfair and we're certainly not going to change ISP for this reason - WE don't spam afterall. We've talked to both ORBS and PsiNet, and we think that ORBS are the ones with the problem - their service excludes spam at the cost of a huge amount of legitimate content.

We can email to a different address if you have one that isn't ORBS "protected" - just send me the details.

Rob