As you may know there has been a problem with sending outbound mail through Obelisk. It appears that postfix has not been sending to cc'd recipients. I.e. The 'To:' addressee recieves the mail fine but any 'cc:' addressee's do not recieve the mail.
The current plan to resolve this is to move the smtp-relay functionality to a seperate postfix instance. Which is kinda how it works at the moment (mail is recieved by the main instance and redirected to another listener on a local address for outbound delivery).
Hopefully will have this sorted in the next day or two.
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Update
Hopefully resolved. Point your client to smtp-relay.newswall.org.uk and give it a go. Authentication is as before. Please test to your satisfaction before you start using it for anything important.