PowerScale: Isilon: Unable to send CELOG email event alerts

When configuring SMTP Event Channel and alerting on the PowerScale cluster, the alert email might fail to send if the customer is using SMTP Port 25, and Use encryption is set as default in email settings.

Possible errors related to SMTP security configurations:

/var/log/messages:
2024-09-07T02:40:17.117197+00:00 <1.4> isilon-1(id1) /isi_celog_alerting[64221]: Unable to send to ['isilon@isilon.com'] through '1.2.3.4': STARTTLS extension not supported by server.
2024-09-07T02:40:17.117920+00:00 <3.3> isilon-1(id1) celog_alerting: channels[64221:channels.py:281] ERROR:Could not send email notification: All SMTP hosts (1.2.3.4) failed to deliver to ['isilon@isilon.com']

In version 9.5.0.0 and later, Use Encryption defaults to True in email settings. You must either disable that in global email settings or a specific channel if the SMTP server does not use STARTTLS encryption.

It might show as below on a live cluster:

Isilon-1# isi email view
          Mail Relay: 1.2.3.4
           SMTP Port: 25   <<
         Mail Sender: Isilon@isilon.com
        Mail Subject: 
       Use SMTP Auth: No
  SMTP Auth Username:
      Use Encryption: Yes   << it's enabled as default
          Batch Mode: none
       User Template:

Isilon-1# isi event channels view <ChannelName>
     ...
     SMTP Host: 1.2.3.4
     SMTP Port: 25
 SMTP Use Auth: -
 SMTP Username: -
 SMTP Password: -
 SMTP Security: -    << You have to explicit set it to None if you don't need the encryption.

If the customer uses the global SMTP server settings, you could turn off --use-encryption with the following command:

# isi email settings modify --use-encryption=false

If they manually configured SMTP server settings in the SMTP channel, you could change the smtp-security to NONE for this channel:

# isi event channels modify --smtp-security=NONE <ChannelName>