Hi! Sebastian's patch touches only anonymous-ftp-master, but there are other FTP hosts with the same problem. These days, with the depletion of IPv4 addresses, this affects pretty much everyone who uploads from their home connection. Thus, here's my version of the patch.
Also, as you haven't done an upload of dupload for almost 5 years, would you have something against a NMU with this bug (and probably others)? -- A tit a day keeps the vet away.
--- dupload.conf~ 2011-02-24 00:41:58.000000000 +0100 +++ dupload.conf 2016-01-14 07:08:23.975176394 +0100 @@ -74,6 +74,7 @@ incoming => "/pub/UploadQueue/", # The dinstall on ftp-master sends emails itself dinstall_runs => 1, + passive => 1, }; # see http://backports.debian.org/Contribute/ for more information @@ -81,6 +82,7 @@ fqdn => "backports-master.debian.org", incoming => "/pub/UploadQueue/", dinstall_runs => 1, + passive => 1, }; # see http://www.debian.org/devel/debian-volatile/ for more information @@ -100,6 +102,7 @@ incoming => "/pub/UploadQueue/DELAYED/$delay-day/", # The dinstall on ftp-master sends emails itself dinstall_runs => 1, + passive => 1, }; # Mentors upload queue, see @@ -132,6 +135,7 @@ # # files pass on to dinstall on security which sends emails itself # dinstall_runs => 1, # nonus => 1, +# passive => 1, #};