2017-07-27 11:20:25 1dZoIA-0003hY-Oi == firstname.lastname@example.org R=dnslookup defer (-1): host lookup did not complete 2017-07-27 11:20:25 1dafu5-0001k3-LG <= <> R=1dZoIA-0003hY-Oi U=Debian-exim P=local S=1201 T="Warning: message 1dZoIA-0003hY-Oi delayed 48 hours" 2017-07-27 11:20:41 1dafuD-0001k6-NO DKIM: d=sending-domain.com s=default c=simple/simple a=rsa-sha256 [verification succeeded] 2017-07-27 11:20:41 1dafuD-0001k6-NO <= <> H=localhost (mail.sending-domain.com) [127.0.0.1]:55325 I=[127.0.0.1]:10025 P=esmtp S=1938 id=E1dafu5-0001k3-LG@mail.sending-domain.com T="Warning: message 1dZoIA-0003hY-Oi delayed 48 hours" 2017-07-27 11:20:41 1dafuD-0001k6-NO ** email@example.com: Unknown user 2017-07-27 11:20:41 1dafuD-0001k6-NO Frozen (delivery error message) 2017-07-27 11:20:41 1dafu5-0001k3-LG => firstname.lastname@example.org R=dkimproxy T=dkimproxy_smtp H=localhost [127.0.0.1]:10027 DT=16s 2017-07-27 11:20:41 1dafu5-0001k3-LG Completed
I have replaced the domain names and email addresses from that log. I am trying to work out what is happening.
It seems like the bounce message is frozen. When I manually (using the command line) send an email to the bounce address, it arrives. But in this particular case we are using Sendblaster to send messages to our clients.
I don't understand why 1dafuD-0001k6-NO is frozen but 1dafu5-0001k3-LG is completed.