Comment 27 for bug 1974214

It worked for you first of all in the sense that the remote party did not defer, which makes the test irrelevant.

The remote party which accepted your message does not seem to be my server, nor was "<email address hidden>" the *exact* sender address which my ACL is configured to defer, despite your request to be exact, but that has been added now.

In either case I really did mean it when I said this bug is triggered by the first remote server responding with a deferral and you're now more than welcome to test against my own servers by sending a message from <email address hidden> to <email address hidden>,

$ dig +short gedalya.net mx
10 mail.gedalya.net. <-- will defer
20 mx2.gedalya.net. <-- will accept, but the sending queue runner should crash