The arguments for a HYPERLINK() worksheet function seem to be limited to 256
characters. Is there a workaround for this?

I need to embed functions like this
?subject=My Subject&body="&A1)
in a worksheet, and I need it to accept very long body arguments. If the
argument in this case gets much longer than 200 characters, the function
becomes a #VALUE.

Also, I can't use macros because of all the security issues the worksheet
users will encounter.