Unable to send email alert notification Via SMTP relay

Products

• VMware vCenter Server

Issue/Introduction

Unable to send email alert notification via SMTP relay .

Environment

vCenter 7.x,8.x

Cause

• messages.log

   
  [YYYY-MM-DDTHH:MM:SS] localhost auditd[1766]: Audit daemon rotating log files
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[16710]: My unqualified host name (localhost) unknown; sleeping for retry
  [YYYY-MM-DDTHH:MM:SS] localhost CROND[16835]: (root) CMD ( test -x /usr/sbin/vpxd_periodic && /usr/sbin/vpxd_periodic >/dev/null 2>&1)
  [YYYY-MM-DDTHH:MM:SS] localhost CROND[16836]: (root) CMD (. /etc/profile.d/VMware-visl-integration.sh; /usr/lib/applmgmt/backup_restore/scripts/SchedulerCron.py >>/var/log/vmware/applmgmt/backupSchedulerCron.log 2>&1)
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[17484]: My unqualified host name (localhost) unknown; sleeping for retry
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[17487]: My unqualified host name (localhost) unknown; sleeping for retry
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[19343]: My unqualified host name (localhost) unknown; sleeping for retry
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[19350]: My unqualified host name (localhost) unknown; sleeping for retry
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[11990]: unable to qualify my own domain name (localhost) -- using short name
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[11994]: unable to qualify my own domain name (localhost) -- using short name
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[11990]: 46P7XFlc011990: [email protected], size=1045, class=0, nrcpts=1, msgid=<202407250733.46P7XFlc011990@localhost>, relay=root@localhost
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[11994]: 46P7XGoR011994: [email protected], size=1049, class=0, nrcpts=1, msgid=<202407250733.46P7XGoR011994@localhost>, relay=root@localhost
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[19608]: 46P7XGiM019608: from=<[email protected]>, size=1256, class=0, nrcpts=1, msgid=<202407250733.46P7XFlc011990@localhost>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
  [YYYY-MM-DDTHH:MM:SS] localhost sendmail[19608]: 46P7XGiM019608: to=<[email protected]>, delay=00:00:00, mailer=relay, pri=31256, dsn=4.4.3, stat=queued

  Based on the logs the messages state is in queue only, It is trying to search for SMTP gateway. (It has never come out side from queue

Resolution

-DNS record is created for both side (VC and SMTP)
-Add DNS in VAMI - Networking page. (Makesure we do have vCenter snapshot created)
-once done check on vCenter ssh 

cat /etc/resolve.conf    (DNS entry is created)

-Make sure we have FQDN entry in /etc/hosts file

service-control --stop --all && service-control --start --all

sudo systemctl restart sendmail

systemctl status sendmail