Firewall Egress Rules: Allow outbound TCP 587/465 access to the SMTP relay.
Minimize Credential Permissions: Grant only the permissions needed to send emails. Avoid reusing personal email passwords and prioritize "app-specific passwords".
Password Management: Store the SMTP password or API Key securely, restrict access, and rotate it periodically.
Sender Policy: The actual From address should belong to a domain you have verified. Avoid using public domains (such as @gmail.com) as the From address for a business system.
