diff --git a/SubModules/postfix/conf.sh b/SubModules/postfix/conf.sh
index fab9531..f0448f5 100644
--- a/SubModules/postfix/conf.sh
+++ b/SubModules/postfix/conf.sh
@@ -36,7 +36,7 @@ EOF
 #    OpenDKIM    #
 ##--------------##
 
-useradd -G opendkim postfix
+usermod –a –G opendkim postfix
 rm -rf /etc/opendkim.d
 mkdir -p /etc/opendkim.d/keys
 chown opendkim:opendkim /etc/opendkim.d/keys -R