5166 sendmail package should be replaceable

*** 618,628 ****
          if (hflag)
                  extra += 2;
  #endif /* SENDMAIL */
          top = (char **) salloc((t + extra) * sizeof (char *));
          ap = top;
!         *ap++ = "mail";
          if (rflag != NOSTR) {
                  *ap++ = "-r";
                  *ap++ = rflag;
          }
  #ifdef SENDMAIL
--- 618,628 ----
          if (hflag)
                  extra += 2;
  #endif /* SENDMAIL */
          top = (char **) salloc((t + extra) * sizeof (char *));
          ap = top;
!         *ap++ = "sendmail";
          if (rflag != NOSTR) {
                  *ap++ = "-r";
                  *ap++ = rflag;
          }
  #ifdef SENDMAIL