Emails are not sent from vCenter Server Appliance after an Alert/Event is triggered.
search cancel

Emails are not sent from vCenter Server Appliance after an Alert/Event is triggered.

book

Article ID: 321441

calendar_today

Updated On:

Products

VMware vCenter Server

Issue/Introduction

  • Alert/Event is triggered but action email is not being sent from vCenter Server Appliance.
  • In /var/log/vmware/messages, you see entries similar to
sendmail[24224]: <VC>: [email protected], size=548, class=0, nrcpts=1, msgid=<##@vcsa65.example.com>, relay=root@localhost
sendmail[24224]: <VC>: [email protected], delay=00:01:05, mailer=esmtp, pri=30548, dsn=4.4.3, stat=queued
sendmail[918]: <VC>: from=<xyz.com>, size=516, class=0, nrcpts=1, msgid=<test.example.com>, relay=root@localhost
sendmail[920]: <VC>: ruleset=check_mail, arg1=<[email protected]>, relay=photon-machine [127.0.0.1], reject=451 4.1.8 Domain of sender address [email protected] does not resolve
sendmail[918]: <VC>: [email protected], [email protected] (0/0), delay=00:01:07, xdelay=00:01:07, mailer=relay, pri=30516, relay=[127.0.0.1] [127.0.0.1], dsn=4.0.0, stat=Deferred: 451 4.1.8 Domain of sender address [email protected] does not resolve
  • A test email using sendmail fails with the below error: 
$> echo "Subject: test" | sendmail -v [[email protected]]
example.com: Name server timeout
[email protected]... Transient parse error -- message queued for future delivery
[email protected]... queued

Environment

vCenter Server 7.x 

vCenter Server 8.x

Cause

This issue occurs when send mail is failing to resolve the configured recipients domain or if the relay host is rejecting the senders email address (root@localhost).

Resolution

Note1: Prior to applying resolution ensure you take an offline backup or snapshot of the vCenter Server Appliance. 
Note2: The applied configuration change may be lost after upgrade. In such case, Please apply the steps again.

To resolve the issue, force vCenter Server to hand off all email outbound to a designated central mail server (like an internal corporate relay).

1. Connect to vCenter Server Appliance via ssh.
2. Edit sendmail.service using the vi editor.

vi /lib/systemd/system/sendmail.service (This is for 7.0 and later versions)
 
In earlier releases, the file may be at different directory. (/etc/systemd/system/sendmail.service) 

3. Alter the After entry under [Unit] section to be as follows:

[Unit]
    :
After=syslog.target network.target systemd-resolved.service
 
4. Save the changes and close the editor.
5. Open sendmail.mc using vi editor:

/etc/mail/sendmail.mc

6. Add following entry after OSTYPE:

FEATURE(`nocanonify')dnl
define(`SMART_HOST', `[Your_mail_host]')dnl

Note: change Your_mail_host to reflect the correct mail server hostname.

7. Save the change and close the editor.
8. Next, edit submit.mc using the vi editor.

vi /etc/mail/submit.mc

9. Add the following line at the end of the define entries:

define(`confDIRECT_SUBMISSION_MODIFIERS', `C')dnl

10. Save the change and close the editor.
11. Verify that local hostname is present and is resolvable in hosts file.

/etc/hosts

12. Execute following command and generate new .cf file

cd /etc/mail
m4 m4/cf.m4 sendmail.mc > sendmail.cf
m4 m4/cf.m4 submit.mc > submit.cf

13. Reload system daemon and restart sendmail.

systemctl daemon-reload
systemctl restart sendmail
 

At this point, the vCenter should be able to send emails to the mail server; however, the emails will be sent as root@localhost. Validate it by sending a test alarm and checking the messages log under /var/log/vmware/.

Once validated: 

  1. Make a backup copy of the submit.cf file
  2. Submit.cf is a read-only file. The permissions on this file must first be changed with this command: 
chmod 644 /etc/mail/submit.cf
  1. ​​​​​ Edit submit.cf with the vi editor
vi /etc/mail/submit.cf
  1. After the "DS", enter the FQDN of the mail server
  2. Save the file
  3. Change the file's permission back to the original permissions:
chmod 444 /etc/mail/submit.cf

For example, if the mail server FQDN is: mailserver.xyzdomain.com
​# "Smart" relay host (may be null or contain IP address)
DS[mailserver.xyzdomain.com]
DS[IP address of mailserver]
  1. Restart sendmail daemon using systemd.

systemctl restart sendmail


Verify In vCenter GUI, Menu -> Inventory -> Configure -> General (under Settings)->Mail->Mail Server.

Additional Information

This action plan would also work in a case where we have VC trying to route the email alerts to localhost instead of SMTP server.
You would see something like following in the messages.log file:

YYYY-MM-DDTHH:MM:SS vCENTER-FQDN sendmail[7137]: vc: [email protected] [email protected]  (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=31012, relay=[127.0.0.1] [127.0.0.1], dsn=4.4.1, stat=Deferred: Connection refused by [127.0.0.1]


YYYY-MM-DDTHH:MM:SS vCENTER-FQDN sendmail[7136]: vc: from=[email protected], size=1012, class=0, nrcpts=1, msgid=<[email protected]>, relay=root@localhost


YYYY-MM-DDTHH:MM:SS vCENTER-FQDN sendmail[7136]: vc: to=[email protected];, ctladdr=[email protected]  (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=31012, relay=[127.0.0.1] [127.0.0.1], dsn=4.4.1, stat=Deferred: Connection refused by [127.0.0.1]

Powered by Wolken Software