zendframework/zf2 — pull request #1551 by Steffen185 (2012-06-22 11:20:10+00:00)
Title: Rename email header "Mime-Version" to "MIME-Version"

In ZF1 this header was named "MIME-Version". In ZF2 this has been changed to "Mime-Version". Mail headers are case-insensitive, but who knows how many buggy clients are out there and the RFC uses "MIME-Version", too: http://tools.ietf.org/html/rfc2045