I managed to get my custom transport running (see my previous message). Now I would like to write 3 more transports: smtp, pop3 and imap4 (in distant future). The problem is addressing. What should be message address? I got it up and runnign if the message is addressed to soap.pop://myemail@example.net/ and via is set to soap.smtp://myemail@example.net/. This addressing however does not scale well to imap because sender would have to know which protocol will be used by receiver. Ideally I would like to address the message to mail://myemail@example.net/ and receive it arbitrary protocol. How can I achieve this?