SMTP notification error "Could not convert socket to TLS"

Plugins Alerting
1

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
2.18.0

Describe the issue:

my smtp server requires start_tls.
I tried to send a test email based on my smtp configuration, got:

“delivery_status”: {
“status_code”: “424”,
“status_text”: “sendEmail Error, status:Could not convert socket to TLS”
}

my smtp server is protected by a private CA.

how to config the CA root cert into notification plugin, so the smtp can have tls1.3 handshake with opensearch?
and if possible to specify to use smtp:// as the protocal? i think the smtps:// may not supported by my smtp server
Configuration:
{
“config_id”: “smtp”,
“config”: {
“name”: “smtp”,
“description”: “”,
“config_type”: “smtp_account”,
“is_enabled”: true,
“smtp_account”: {
“host”: “”,
“port”: 587,
“method”: “start_tls”,
“from_address”: “”
}
}
}

{
“config_id”: “email-notification”,
“config”: {
“name”: “email-notification”,
“description”: “email notification”,
“config_type”: “email”,
“is_enabled”: true,
“email”: {
“email_account_id”: “smtp”,
“recipient_list”: [
{
“recipient”: “”
}
],
“email_group_id_list”:
}
}
}
Relevant Logs or Screenshots:

2

issue resolved by following What CA is used by notifications channels? - Plugins / Alerting - OpenSearch to add the CA cert to /usr/share/opensearch/jdk/lib/security/cacerts