In der KBASE habe ich nur das dazu gefunden - evtl. ist es aber die Ursache:
Title:
Mail Body Field Created from Web Browser May Display as HTML Code in Certain Mail Programs
Product: Lotus Notes > Lotus Notes > Version 5.x
Platform(s): Platform Independent
Date: 13.09.2004
Doc Number: 1098582
Problem
Certain mail servers, such as cc:Mail 6.0, UNIX Sendmail or Microsoft Mail 2.0, cannot read MIME messages that contain Content-Type: text/html in the header. The HTML code tags display along with the message. For messages with this content-type, the client should invoke its HTML parser to allow the HTML tags to be rendered as formatted text; however, if the mail client or server is unable to render the HTML, the body text includes HTML tags.
Solution
This is a limitation of the receiving mail program. To prevent messages from being created like this, the Body field properties in the Notes Memo form can be changed to force a content-type of plain/text.
To do this, open the Field Properties dialog box for the Body field on the Memo form and switch to the Information tab. Change the Web Access - Display setting from "Using Java Applet" to "Using HTML."
This workaround does, however, prevent the sender from being able to compose rich text. The "Using Java Applet" option enables the rich text editor applet when the document is edited from the web.
Supporting Information:
This only affects messages created from a web browser. Messages created from a Notes client instead of a browser are created with a Content-type of plain/text as the default.
Andreas