Note that this does not apply to Cyrus versions starting with 2.1.14 (the interoperability problem was solved). Note that due to the unique nature of this problem the later versions have a rfc2046_strict ImapdConf? option which will restore the old behavior.

RFC 2046 has some text which, if interpreted literally, does not allow outer mime boundrys to be substrings of inner mime boundries. Eudora, as it happens, creates messages which have just that format. The problem is that earlier versions of the MIME spec did not contain this restriction, so 2046 is not backwards compatible (in a literal interpretation).

After discussions with other implementors within the IETF, it was decided that Eudora's behavior was clearly broken, Cyrus's behavior was unfriendly to interoperability but technically correct, and RFC 2046 probably needs a clarification. Thus, we corrected the behavior in Cyrus with an option to revert to the strict behavior if a site so desires.

-- RobSiemborski? - 24 Jul 2003