SMTP submission fails with Office 365

[FeoZ]

Describe the bug
Configuring email notifications in ThreatMapper with Microsoft 365 (SMTP) fails with the error:
tls: first record does not look like a TLS handshake

The exact same Microsoft 365 SMTP credentials work in other applications, so this appears specific to ThreatMapper’s SMTP/TLS handling.

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To Reproduce

1. Go to Settings → email configuration → Add configuration
2. Select SMTP as the provider
3. Fill in:
   • Email/Username: noreply-threatmapper@company.com
   • Password: mailbox password
   • SMTP server: smtp.office365.com
   • Port: 587 (also tested with 465)
4. Click Send Test Email
5. Observe the error: tls: first record does not look like a TLS handshake

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Expected behavior
ThreatMapper should successfully send the test email using Microsoft 365 SMTP when valid credentials are provided.

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Screenshots

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Components/Services affected

• UI/Frontend
• API/Backend
• Agent
• Deployment/YAMLs
• CI/CD Integration
• Other (specify)

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Additional context

• Microsoft 365 supports:
  • Port 587 with STARTTLS (preferred)
• ThreatMapper fails on 587 with the above TLS error, which suggests the client may be attempting implicit TLS on 587 instead of performing a STARTTLS upgrade.
• SMTP AUTH is enabled for the mailbox and the account is licensed.
• Reference Documentation

Environment details

• ThreatMapper version: 2.5.7
• Deployment: Kubernetes - Helm chart deepfence-console, version: 2.5.7
• Network: outbound TCP 587/465 open from the ThreatMapper host/pod