It's not your fault.

I have a vague recollection that in Notes (when I was forced to use it)
they can control the format of the mail.  Their setting is wrong. Ask
them to look for an option (or get help from their computer support) to
make it a standard, industry standard-formatted mail.  Not HTML. Not
RTF. Not Lotus.  Just something "standard".

Hope this is useful to you.  Let us know.

rms