Linux Postfix Troubleshooting

 Question : Some users of the monitoring app have reported issues with xFusionCorp Industries mail server. They have a mail server in Stork DC where they are using postfix mail transfer agent. Postfix service seems to fail. Try to identify the root cause and fix it.

Please Note :-  Perform the below commands based on your question  server,  user name & other details might differ . So please read task carefully before executing. All the Best 👍

Solution:  

1. Login on   Mail  server as per the task and switch root user

thor@jump_host /$ ssh groot@stmail01 The authenticity of host 'stmail01 (172.16.238.11)' can't be established. ECDSA key fingerprint is SHA256:SySamszyWhhLGFiybhGBqfrr8g55wS/3e37ZpBOvICs. ECDSA key fingerprint is MD5:6d:31:18:2a:f9:07:f3:29:dd:0a:d3:1f:6e:04:0a:db. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added 'stmail01,172.16.238.17' (ECDSA) to the list of known hosts. groot@stmail01's password: [groot@stmail01 ~]$ sudo su -  We trust you have received the usual lecture from the local System Administrator. It usually boils down to these three things:      #1) Respect the privacy of others.     #2) Think before you type.     #3) With great power comes great responsibility.  [sudo] password for groot: [root@stmail01 ~]#

2. Start postfix service , check status with -l for details error output 

[root@stmail01 ~]# systemctl start postfix Job for postfix.service failed because the control process exited with error code. See "systemctl status postfix.service" and "journalctl -xe" for details. [root@stmail01 ~]# [root@stmail01 ~]# systemctl status postfix -l ● postfix.service - Postfix Mail Transport Agent    Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)    Active: failed (Result: exit-code) since Tue 2021-06-22 14:55:33 UTC; 6s ago   Process: 383 ExecStart=/usr/sbin/postfix start (code=exited, status=1/FAILURE)   Process: 382 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)   Process: 379 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=75)   Jun 22 14:55:31 stmail01.stratos.xfusioncorp.com systemd[1]: Starting Postfix Mail Transport Agent... Jun 22 14:55:31 stmail01.stratos.xfusioncorp.com aliasesdb[379]: /usr/sbin/postconf: fatal: parameter inet_interfaces: no local interface found for ::1 Jun 22 14:55:32 stmail01.stratos.xfusioncorp.com aliasesdb[379]: newaliases: fatal: parameter inet_interfaces: no local interface found for ::1 Jun 22 14:55:32 stmail01.stratos.xfusioncorp.com postfix/sendmail[381]: fatal: parameter inet_interfaces: no local interface found for ::1 Jun 22 14:55:32 stmail01.stratos.xfusioncorp.com postfix[383]: fatal: parameter inet_interfaces: no local interface found for ::1 Jun 22 14:55:33 stmail01.stratos.xfusioncorp.com systemd[1]: postfix.service: control process exited, code=exited status=1 Jun 22 14:55:33 stmail01.stratos.xfusioncorp.com systemd[1]: Failed to start Postfix Mail Transport Agent. Jun 22 14:55:33 stmail01.stratos.xfusioncorp.com systemd[1]: Unit postfix.service entered failed state. Jun 22 14:55:33 stmail01.stratos.xfusioncorp.com systemd[1]: postfix.service failed. [root@stmail01 ~]#

3. As we identify the issue in configuration file edit and do the changes

[root@stmail01 ~]# cat /etc/postfix/main.cf |grep inet_interface # The inet_interfaces parameter specifies the network interface inet_interfaces = all #inet_interfaces = $myhostname #inet_interfaces = $myhostname, localhost inet_interfaces = localhost # the address list specified with the inet_interfaces parameter. # receives mail on (see the inet_interfaces parameter). # to $mydestination, $inet_interfaces or $proxy_interfaces. # - destinations that match $inet_interfaces or $proxy_interfaces, # unknown@[$inet_interfaces] or unknown@[$proxy_interfaces] is returned [root@stmail01 ~]# [root@stmail01 ~]# vi /etc/postfix/main.cf [root@stmail01 ~]# cat /etc/postfix/main.cf |grep inet_interface # The inet_interfaces parameter specifies the network interface inet_interfaces = all #inet_interfaces = $myhostname #inet_interfaces = $myhostname, localhost #inet_interfaces = localhost # the address list specified with the inet_interfaces parameter. # receives mail on (see the inet_interfaces parameter). # to $mydestination, $inet_interfaces or $proxy_interfaces. # - destinations that match $inet_interfaces or $proxy_interfaces, # unknown@[$inet_interfaces] or unknown@[$proxy_interfaces] is returned [root@stmail01 ~]#

4. Post configuration saved start the services and check the status 

[root@stmail01 ~]# systemctl start postfix [root@stmail01 ~]# [root@stmail01 ~]# systemctl status postfix ● postfix.service - Postfix Mail Transport Agent    Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)    Active: active (running) since Tue 2021-06-22 14:59:45 UTC; 16s ago   Process: 475 ExecStop=/usr/sbin/postfix stop (code=exited, status=0/SUCCESS)   Process: 504 ExecStart=/usr/sbin/postfix start (code=exited, status=0/SUCCESS)   Process: 503 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)   Process: 501 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=0/SUCCESS)  Main PID: 575 (master)    CGroup: /docker/050a5d787eedc1731e809d002d6f548be599723012d6b80fd344d807a45da4db/system.slice/postfix.service            ├─575 /usr/libexec/postfix/master -w            ├─576 pickup -l -t unix -u            └─577 qmgr -l -t unix -u  Jun 22 14:59:45 stmail01.stratos.xfusioncorp.com systemd[1]: Starting Postfix Mail Transport Agent... Jun 22 14:59:45 stmail01.stratos.xfusioncorp.com postfix/master[575]: daemon started -- version 2.10.1, configuration /e...fix Jun 22 14:59:45 stmail01.stratos.xfusioncorp.com systemd[1]: Started Postfix Mail Transport Agent. Hint: Some lines were ellipsized, use -l to show in full. [root@stmail01 ~]#

5. validate the task by telnet the port 25 

thor@jump_host /$ telnet stmail01 25 Trying 172.16.238.17... Connected to stmail01. Escape character is '^]'. 220 stmail01.stratos.xfusioncorp.com ESMTP Postfix Connection closed by foreign host. thor@jump_host /$

6. Click on Finish & Confirm to complete the task successful

Happy Learning!!!!

Apart from this if you need more clarity,  I have made a  tutorial video on this , please go through and share your comments. Like and share the knowledge