[Zope] Netscape/RTF problem

I am currently experiencing problems using Zope to publish RTF files in a mixed browser environment (Netscape and IE). Netscape uploads RTF files with a mime type of "application/rtf", Internet Explorer uploads RTF files with a mime type of "text/richtext". The Netscape browser does not appear to handle RTF files uploaded using Internet Explorer correctly - the raw RTF data is displayed in the browser window. Netscape does correctly handle RTF documents with mime type=application/rtf, however. Internet Explorer works correctly with both mime types. Has anybody else come across this problem?