#30 Opendkim header limite of 65536 bytes is too restrictive and the resulting error in postfix is not easily understandable
Hi,
Some of our users are receiving messages from the European Union that are sent to many recipients. The recipients are not send as BCC, but in the To . The resulting message header has more than 70000 bytes, so it is larger as the opendkim hard limit of 65536 bytes.
Code: #define DEFMAXHDRSZ 65536
Opendkim error:
opendkim[26520]: too much header data
Postfix error:
milter-reject: END-OF-MESSAGE from smtp30.ep.europa.eu[136.173.162.208]: 4.7.1 Service unavailable - try again later; from=<**> to=<**> proto=ESMTP helo=<smtp30.ep.europa.eu>
The postfix error message is not easily understandable. It should return something like "too much header data" instead of "4.7.1 Service unavailable - try again later".
Why is this value configured to 65536? Could it be changed to a value similar to those used and supported by postfix and other MTAs? Could the error message returned by the DKIM Milter indicate the real reason?
Best regards,
This issue is reported in the Debian bug tracker (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=838767) and I have just filed another ticket for the Fedora EPEL package (https://bugzilla.redhat.com/show_bug.cgi?id=1379647).
The patch proposed in the Debian bug tracker resolves the issue for me. Would be good to have an upstream solution for this issue though.
Last edit: David Sommerseth 2016-09-27
This has been closed downstream because there's already the configuration option MaximumHeaders.