Implement Microsoft OAuth2 authentication for SMTP

[purplesmoke05]

📌 Description

This pull request adds support for Microsoft OAuth2 (XOAUTH2) authentication for SMTP email sending, in addition to the existing password-based and Amazon SES methods. It introduces new configuration options, updates the mail sending logic to handle OAuth2 tokens, and provides unit tests to ensure correct behavior for both authentication methods. Documentation is also updated to reflect the new options and configuration matrix.

4. Unit Testing

• Added comprehensive unit tests for the Mail class to verify both password and XOAUTH2 authentication flows, using mocks to ensure correct SMTP interactions and token handling.

✅ Related Issues

• Close [FEATURE] Support Microsoft 365 email sending via OAuth (SMTP XOAUTH2 and/or Microsoft Graph) #1699

🔄 Changes

Major additions and changes:

1. Microsoft OAuth2 (XOAUTH2) SMTP Support

• Added support for XOAUTH2 authentication with Microsoft (Azure AD/Entra ID) by introducing new environment variables (SMTP_MS_TENANT_ID, SMTP_MS_CLIENT_ID, SMTP_MS_CLIENT_SECRET, SMTP_MS_REFRESH_TOKEN) and updating the configuration and documentation accordingly. [1] [2] [3] [4]
• Implemented a TokenProvider abstraction and a MicrosoftTokenProvider class to securely retrieve and cache Microsoft access tokens for SMTP authentication.

2. Mail Sending Logic Updates

• Modified the Mail class in mail.py to support both password and XOAUTH2 authentication methods, including logic to perform XOAUTH2 authentication with the SMTP server using the access token. [1] [2] [3]

3. Configuration and Documentation

• Added new environment variables and updated ENV_LIST.md to document all supported SMTP authentication methods, Microsoft OAuth2 settings, and provided a configuration matrix for clarity. [1] [2] [3] [4] [5]

📌 Checklist

• I have added tests where necessary.
• I have updated the documentation where necessary.

[kyken]

LGTM

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
app
config.py	107	5	95%	61–62, 66, 137, 178
app/model/db
messaging.py	21	0	100%
app/model/mail
mail.py	80	13	83%	67, 73, 80–81, 94, 114–115, 121, 133–134, 154, 156, 159
token_provider.py	66	19	71%	46, 75–77, 80–81, 83–84, 87, 89, 95, 109–110, 113–115, 118, 125–126
tests/app/model/mail
test_mail_unit.py	39	0	100%
test_token_provider.py	96	0	100%
tests/batch
processor_Send_Mail_test.py	122	0	100%
TOTAL	45801	1602	96%

Tests	Skipped	Failures	Errors	Time
1538	0 💤	0 ❌	0 🔥	12m 13s ⏱️