[Evolution] what are all of the valid arguments for mailto?

["Brian J. Murrell" <brian interlinx bc ca>]

I'm wondering what all of the valid arguments that one can put in an
evolution "mailto:..."; invocation.  So far I have found:

      * attach
      * cc
      * bcc
      * subject

Are there any more?  Specifically, can I set the source account (i.e.
which of the many From: selections)?  How about the attachment
parameters such as Content-type (assuming evo doesn't always get it
right), "name", etc.?

Thanx!

b.