I am not entirely clear on how this issue arose, so I shall provide you with the SMTP configuration details from my app.yml file for your reference:
# WARNING the char '#' in SMTP password can cause problems!
DISCOURSE_SMTP_ADDRESS: smtp.larksuite.com #The SMTP server address
DISCOURSE_SMTP_PORT: 587
DISCOURSE_SMTP_USER_NAME: system@starorigin.net #Default Sending Email Address
DISCOURSE_SMTP_PASSWORD: abcdef #The default SMTP password must be entered accurately.
DISCOURSE_SMTP_ENABLE_START_TLS: true
#DISCOURSE_SMTP_DOMAIN: discourse.example.com # (required by some providers)
DISCOURSE_NOTIFICATION_EMAIL: system@starorigin.net # (The default notification email address)