zed: fix sending emails (#12292)

Commit 6fc3099 broke the quoting when invoking the mail program, revert
that change.

Signed-off-by: Laurențiu Nicola <lnicola@dend.ro>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>

cmd/zed/zed.d/zed-functions.sh

@@ -267,7 +267,7 @@ zed_notify_email()
                 -e "s/@SUBJECT@/${subject}/g")"
 
     # shellcheck disable=SC2086
-    ${ZED_EMAIL_PROG} ${ZED_EMAIL_OPTS} < "${pathname}" >/dev/null 2>&1
+    eval ${ZED_EMAIL_PROG} ${ZED_EMAIL_OPTS} < "${pathname}" >/dev/null 2>&1
     rv=$?
     if [ "${rv}" -ne 0 ]; then
         zed_log_err "$(basename "${ZED_EMAIL_PROG}") exit=${rv}"