-ifdef(`confSMTP_MAILER',, `define(`confSMTP_MAILER', `esmtp')')dnl
-define(`_SMTP_', `confSMTP_MAILER')dnl for readability only
+ifdef(`confSMTP_MAILER',, `define(`confSMTP_MAILER', `smtp')')dnl
+ifdef(`confLOCAL_MAILER',, `define(`confLOCAL_MAILER', `local')')dnl
+ifdef(`confRELAY_MAILER',,
+ `define(`confRELAY_MAILER',
+ `ifdef(`_MAILER_smtp_', `relay',
+ `ifdef(`_MAILER_uucp', `suucp', `unknown')')')')dnl
+define(`_SMTP_', `confSMTP_MAILER')dnl for readability only
+define(`_LOCAL_', `confLOCAL_MAILER')dnl for readability only
+define(`_RELAY_', `confRELAY_MAILER')dnl for readability only