envelope_set_esc_class
envelope_set_esc_class(&evp, ESC_STATUS_PERMFAIL);
envelope_set_esc_class(&evp, ESC_STATUS_OK);
envelope_set_esc_class(&evp, ESC_STATUS_TEMPFAIL);
envelope_set_esc_class(&evp, ESC_STATUS_PERMFAIL);
envelope_set_esc_class(&evp, ESC_STATUS_TEMPFAIL);
void envelope_set_esc_class(struct envelope *, enum enhanced_status_class);