diff --git a/tests/p_postfix/10_postfix_smtp.sh b/tests/p_postfix/10_postfix_smtp.sh
index 7489f6d..b55fc9a 100755
--- a/tests/p_postfix/10_postfix_smtp.sh
+++ b/tests/p_postfix/10_postfix_smtp.sh
@@ -3,6 +3,6 @@
 
 t_Log "Running $0 - Postfix SMTP test."
 
-echo "helo test" | nc -w 3 localhost 25 | grep -q '250'
+echo "helo test" | nc -w 3 127.0.0.1 25 | grep -q '250'
 
 t_CheckExitStatus $?
diff --git a/tests/p_postfix/20_postfix_mta.sh b/tests/p_postfix/20_postfix_mta.sh
index 3103bf2..a7a354d 100755
--- a/tests/p_postfix/20_postfix_mta.sh
+++ b/tests/p_postfix/20_postfix_mta.sh
@@ -5,7 +5,7 @@ t_Log "Running $0 - postfix can accept and deliver local email."
 ret_val=1
 
 # send mail to localhost
-mail=$(echo -e "helo localhost\nmail from: root@localhost\nrcpt to: root@localhost\ndata\nt_functional test\n.\nquit\n" | nc -w 5 localhost 25 | grep queued)
+mail=$(echo -e "helo localhost\nmail from: root@localhost\nrcpt to: root@localhost\ndata\nt_functional test\n.\nquit\n" | nc -w 5 127.0.0.1 25 | grep queued)
 MTA_ACCEPT=$?
 if [ $MTA_ACCEPT == 0 ]
   then
diff --git a/tests/p_postfix/30_postfix_mta_ehlo.sh b/tests/p_postfix/30_postfix_mta_ehlo.sh
index 8b502ed..45c21bf 100755
--- a/tests/p_postfix/30_postfix_mta_ehlo.sh
+++ b/tests/p_postfix/30_postfix_mta_ehlo.sh
@@ -5,7 +5,7 @@ t_Log "Running $0 - postfix can accept and deliver local email using ESMTP."
 ret_val=1
 
 # send mail to localhost
-mail=$(echo -e "ehlo localhost\nmail from: root@localhost\nrcpt to: root@localhost\ndata\nt_functional test\n.\nquit\n" | nc -w 5 localhost 25 | grep queued)
+mail=$(echo -e "ehlo localhost\nmail from: root@localhost\nrcpt to: root@localhost\ndata\nt_functional test\n.\nquit\n" | nc -w 5 127.0.0.1 25 | grep queued)
 MTA_ACCEPT=$?
 if [ $MTA_ACCEPT == 0 ]
   then
diff --git a/tests/p_postfix/40_postfix_sasl.sh b/tests/p_postfix/40_postfix_sasl.sh
index 3ac5c04..4283754 100755
--- a/tests/p_postfix/40_postfix_sasl.sh
+++ b/tests/p_postfix/40_postfix_sasl.sh
@@ -79,7 +79,7 @@ t_ServiceControl dovecot restart
 
 #Running test
 t_Log "Testing if postfix accepts connections and offers AUTH PLAIN"
-echo "ehlo test" | nc -w 3 localhost 25 | grep -q 'AUTH PLAIN'
+echo "ehlo test" | nc -w 3 127.0.0.1 25 | grep -q 'AUTH PLAIN'
 ret_val=$?
 
 # restoring changed files
diff --git a/tests/p_postfix/50_postfix_tls.sh b/tests/p_postfix/50_postfix_tls.sh
index 0e4557f..876226f 100755
--- a/tests/p_postfix/50_postfix_tls.sh
+++ b/tests/p_postfix/50_postfix_tls.sh
@@ -156,7 +156,7 @@ t_ServiceControl dovecot restart
 
 #Running test
 t_Log "Testing if postfix accepts connections and offers STARTTLS"
-echo "ehlo test" | nc -w 3 localhost 25 | grep -q 'STARTTLS'
+echo "ehlo test" | nc -w 3 127.0.0.1 25 | grep -q 'STARTTLS'
 ret_val=$?
 
 # restoring changed files
diff --git a/tests/p_sendmail/30_sendmail_mta_ehlo.sh b/tests/p_sendmail/30_sendmail_mta_ehlo.sh
index 106a3e7..68b6485 100755
--- a/tests/p_sendmail/30_sendmail_mta_ehlo.sh
+++ b/tests/p_sendmail/30_sendmail_mta_ehlo.sh
@@ -5,7 +5,7 @@ t_Log "Running $0 - sendmail can accept and deliver local email."
 ret_val=1
 
 # send mail to localhost
-mail=$(echo -e "ehlo localhost\nmail from: root@localhost\nrcpt to: root@localhost\ndata\nt_functional test\n.\nquit\n" | nc -w 5 localhost 25 | grep accepted)
+mail=$(echo -e "ehlo localhost\nmail from: root@localhost\nrcpt to: root@localhost\ndata\nt_functional test\n.\nquit\n" | nc -w 5 127.0.0.1 25 | grep accepted)
 MTA_ACCEPT=$?
 if [ $MTA_ACCEPT == 0 ]
   then