[PLTFRM-1777]: Add tracking to successful email sends

[rebeccahum]

Description

Adds tracking to successful email sends

Pre-review checklist

Please make sure the items below have been covered before requesting a review:

• This change works and has been tested locally or in Codespaces (or has an appropriate fallback).
• This change works and has been tested on a sandbox.
• This change has relevant unit tests (if applicable).
• This change uses a rollout method to ease with deployment (if applicable - especially for large scale actions that require writes).
• This change has relevant documentation additions / updates (if applicable).
• I've created a changelog description that aligns with the provided examples.

Pre-deploy checklist

• VIP staff: Ensure any alerts added/updated conform to internal standards (see internal documentation).

Steps to Test

1. Sandbox and add the PR code
2. In build_tracks_event_args(), add:

		error_log( sprintf(
			'%s: calling Tracks::record_event( %s, %s )',
			__METHOD__,
			'wpcom_email_send',
			wp_json_encode( $event_args )
		) );

3. ks sandbox logs -f in another screen
4. shell in and do wp_mail( '[email protected]', 'VIP Tracks Test', 'Hello world' );
   Expect to see in the sandbox logs:

[17-Nov-2025 20:59:42 UTC] Automattic\VIP\Mail\VIP_SMTP::build_tracks_event_args: calling Tracks::record_event( wpcom_email_send, {"date_sent":"2025-11-17","email_domain":"example.com","_ut":"anon","_ui":"<ui>","email_id":"<email_id>"} )

[codecov]

Codecov Report

❌ Patch coverage is 34.09091% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 34.81%. Comparing base (e64d608) to head (c07cb18).

Files with missing lines	Patch %	Lines
vip-mail.php	34.09%	29 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #6615      +/-   ##
=============================================
- Coverage      34.82%   34.81%   -0.02%     
- Complexity      5032     5048      +16     
=============================================
  Files            295      295              
  Lines          20743    20783      +40     
=============================================
+ Hits            7224     7235      +11     
- Misses         13519    13548      +29     

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[Copilot]

Pull Request Overview

This PR adds tracking functionality for successful email sends in the VIP Mail system. The implementation integrates with Automattic's Tracks telemetry system to record email send events with relevant metadata.

• Adds tracking of successful email sends via the wp_mail_succeeded action hook
• Refactors mail blocking logic into a reusable is_mail_blocked() method
• Implements event data collection including user identification, email domain, and blog ID

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[PZ01]

Started looking at this w/ Rebecca over Slack, to address a few questions on how it should be implemented. I was given access to VIP to do tests, but it is EOD for me now and will resume tomorrow.