diff --git a/sendmail.spec b/sendmail.spec
index 01b69e6..eeb0966 100644
--- a/sendmail.spec
+++ b/sendmail.spec
@@ -14,7 +14,7 @@
 Summary: A widely used Mail Transport Agent (MTA)
 Name: sendmail
 Version: 8.14.4
-Release: 4%{?dist}
+Release: 5%{?dist}
 License: Sendmail
 Group: System Environment/Daemons
 URL: http://www.sendmail.org/
@@ -408,8 +408,16 @@ touch %{buildroot}%{_sysconfdir}/pam.d/smtp
 rm -rf %{buildroot}
 
 %pre
-%{_sbindir}/useradd -u 47 -d %{spooldir}/mqueue -r -s %{smshell} mailnull >/dev/null 2>&1
-%{_sbindir}/useradd -u 51 -d %{spooldir}/mqueue -r -s %{smshell} smmsp >/dev/null 2>&1
+getent group mailnull >/dev/null || \
+  %{_sbindir}/groupadd -g 47 -r mailnull >/dev/null 2>&1
+getent passwd mailnull >/dev/null || \
+  %{_sbindir}/useradd -u 47 -g mailnull -d %{spooldir}/mqueue -r \
+  -s %{smshell} mailnull >/dev/null 2>&1
+getent group smmsp >/dev/null || \
+  %{_sbindir}/groupadd -g 51 -r smmsp >/dev/null 2>&1
+getent passwd smmsp >/dev/null || \
+  %{_sbindir}/useradd -u 51 -g smmsp -d %{spooldir}/mqueue -r \
+  -s %{smshell} smmsp >/dev/null 2>&1
 exit 0
 
 %postun
@@ -578,6 +586,9 @@ exit 0
 
 
 %changelog
+* Mon May 31 2010 Jaroslav Škarvada <jskarvad@redhat.com> - 8.14.4-5
+- fixed user/group creation
+
 * Tue Mar 02 2010 Jaroslav Škarvada <jskarvad@redhat.com> - 8.14.4-4
 - used noreplace for sasl config
 - used ghost instead of explicit provides