vCenter Server SMTP authentication not supported – how to guide on getting alerts

I recently updated a customer from 5.1 to 6.0 and a couple of days later received a question on how to setup a mail server with SMTP authentication.

This of course is not possible as described in the following KB 2063147

This got me interested to setup a solution that would provide the functionality to allow outgoing email through SMTP relay service in stead of setting up a full fledged local email server.
Here are the steps I took to setup postfix on CentOS to relay outgoing email to 3de party which requires authentication.

  • Install and configured a linux operating systems.
  • Now we need to install and update the packages required for our configuration which includes postfix as well as cyrus-sasl-plain which is not installed by default on CentOS 6+
    • sudo yum install postfix cyrus-sasl cyrus-sasl-plain
  • To make postfix the default MTA in our system lets remove sendmail
    • sudo yum remove sendmail
  • Postfix setup:
    • vi /etc/postfix/
    • Configure server FQDN:
      • mydomain =
      • myhostname =
    • Configure relayhost to email provide smtp server.  Verify the port since might not be default 25 to prevent spamming.
      • relayhost =
      • relaydomain =
    • Configure cyrus-sasl-plain:
      • smtpd_sasl_auth_enable = yes
      • smtpd_sasl_path = smtpd
      • stmpd_sasl_password_maps = hash:/etc/postfix/sasl_passwd
      • smtpd_sasl_type = cyrus
      • smtp_sasl_auth_enable = yes
    • Configure receive mail so that communication can be established from all networks.  If you select inet_interfaces = localhost then can only send from local server.
      • inet_interfaces = all
      • inet_protocols = all
    • Configure additional trust and relay control
      • mynetworks_style = subnet  (if you want to specify specific network subnets)
      • mynetworks_style = host  (if you want to specify specific host names)
      • mynetworks =,
  • Now since our SMTP server requires authentication we need to setup username and password.
    • vi /etc/postfix/sasl_passwd
      • username:password
      • the servername should match exactly what you have entered for relayhost in /etc/postfix/
  • Generate a postfix lookup table
    • postmap hash:/etc/postfix/sasl_passwd
  • Test lookup table which should return username and password
    • postmap -q /etc/postfix/sasl_passwd
  • Verify sasl_passwd and sasl_passwd.db files are read/write enabled for root only to protect the plain text password.
    • chmod 600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
  • Add postfix to be started at boot
    • chkconfig –add postfix
  • start service
    • /etc/init.d/postfix start
  • Send test email.
    • # sendmail -t
    • TO:
    • From:
    • Subject: Test
    • Did you get this email?
    • .
If you check the status of service and get error:  “Master is Dead ButPid File Exists”, verify that you have removed sendmail successfully.
Connection refused when trying to send from vCenter, verify that port 25 is listening on host with # netstat -nlp | grep 25.  If it shows with then it will only allow local connection.  This needs to show so make sure you have inet_interfaces = all.
Some useful links: