vCenter not using SMTP smarthost but DNS

The other day I had scheduled a task for a VM and I wanted to get an email notification about the status of that job. So I configured the notification.

But the next morning I didn’t find a confirmation email in my inbox. Strange!

So I checked the email settings of vCenter and everything looked ok. The mailserver was configured and the sender address. So what could prevent the email from sending?

I checked /var/log/vmware/vpxd.log and found out that it was trying to send email to the mail host that came from the MX record for the domain I used for the recipient. But that was the public mail server and for obvious reasons not reachable from within the LAN. But why did vCenter used the MX record found in DNS? I specified a mail server so please vCenter, use it…

The solution was to edit the file

  1. Go to /etc/mail and edit the file
  2. Look for these lines:
    #"Smart" relay host (may be null)
  3. After the “DS”, enter the FQDN of the smart host you want to use.
    #"Smart" relay host (may be null)
  4. Restart sendmail with this command:
    systemctl restart sendmail.service