Unfotunately Novell ‘broke’ the facility we were used to utilize a MIME (.MME) file as the master document in the personalize mass email applet. We recently reported this as a bug to Novell. I can’t tell you where Novell have prioritized this, or when it might be fixed.
In the meantime, you need to use HTM or TXT files as the master document to the merge, or install a copy of the 6.0.3 client on a machine you wish to use MME files with.
I’ll check the documentation to ensure this is made clear.