-# Log just about everything we can log so that we have the best
-# possible chance of knowing what's going on.
+# If you're in a part of the world where ASCII is not sufficient for most
+# text, then you're probably familiar with RFC2047 message header extensions.
+# By default, Exim adheres to the specification, including a limit of 76
+# characters to a line, with encoded words fitting within a line.
+# If you wish to use decoded headers in message filters in such a way
+# that successful decoding of malformed messages matters, you may wish to
+# configure Exim to be more lenient.
+#
+# check_rfc2047_length = false
+#
+# In particular, the Exim maintainers have had multiple reports of problems
+# from Russian administrators of issues until they disable this check,
+# because of some popular, yet buggy, mail composition software.
+