diff --git a/mail/sendmail/sendmail.conf b/mail/sendmail/sendmail.conf
index d95f8a9ca..2719004b2 100644
--- a/mail/sendmail/sendmail.conf
+++ b/mail/sendmail/sendmail.conf
@@ -58,6 +58,8 @@ sm_main() {
 	# LDAP support
 	if pkginstalled -f openldap; then
 		sm_appenddef "confENVDEF" "-DLDAPMAP"
+		# enable support for ldap referrals
+		sm_appenddef "confENVDEF" "-DLDAP_REFERRALS"
 		sm_appenddef "confLIBS" "-lldap -llber"
 		sm_appenddef "confLIBDIR" "-L$( pkgprefix -r libdir openldap )"
 		sm_appenddef "confINCDIR" "-L$( pkgprefix -r includedir openldap )"