I use perl scripts and they are still working.
I don't use the "-t" flag on sendmail though.
And my open statement is like this:
>open (SENDMAIL, "|$sendmail -f$rcpf $recip");
The "$rcpf" is my sending email address, the "$recip" is the To address.
The "-f" flag from the man page:
>-fname Sets the name of the ``from'' person (i.e., the sender of the
mail). -f can only be used by ``trusted'' users (normally
root, daemon, and network) or if the person you are trying to
become is the same as the person you are.