fxa(email): Add email normalization check to email libs

[vbudhram]

Because

• The auth-server already checks bounces against email aliases (e.g., test+123@gmail.com → test@gmail.com), but the shared email-sender library in libs/accounts/email-sender/ does not

This pull request

• Adds checkBouncesWithAliases method that queries both the normalized root email and a wildcard alias pattern in parallel
• Updates BouncesConfig with aliasCheckEnabled and emailAliasNormalization config fields
• Adds optional email field to Bounce type for deduplication of merged results
• Reuses existing EmailNormalization class from fxa-shared

Issue

Closes: https://mozilla-hub.atlassian.net/browse/FXA-12829

Checklist

• My commit is GPG signed
• Tests pass locally (if applicable)
• Documentation updated (if applicable)
• RTL rendering verified (if UI changed)

Other Information

• Feature is off by default (aliasCheckEnabled: false). No behavior change unless explicitly enabled.
• The underlying DB stored procedure (fetchEmailBounces_4) already uses LIKE, so wildcard queries (test+%@domain.com) work without DB changes.
• Ports the same logic from packages/fxa-auth-server/lib/bounces.js to the shared lib.

[Copilot]

Pull request overview

This PR extends the shared email-sender bounce checking to understand and normalize email aliases, aligning its behavior with the auth-server’s alias-aware bounce logic.

Changes:

• Extend BouncesConfig and Bounce types to support alias-aware checks (aliasCheckEnabled, emailAliasNormalization, optional email on Bounce).
• Introduce checkBouncesWithAliases in Bounces, using EmailNormalization to query both normalized root and wildcard alias addresses in parallel, and merge/deduplicate results.
• Add comprehensive Jest tests in bounces.spec.ts covering alias checks, threshold behavior, deduplication, and non-configured domain behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
libs/accounts/email-sender/src/bounces.ts	Adds alias-aware bounce checking using EmailNormalization, new config fields, and deduplication of normalized/wildcard query results before applying existing bounce rules.
libs/accounts/email-sender/src/bounces.spec.ts	Adds tests for alias-aware scenarios (on/off switch, thresholds, deduplication, and non-configured domains) to validate the new logic and config options.

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[Copilot]

This test’s description and inline comment state that for non-configured domains, both bounce queries should use the original email, but the expectations only assert that findByEmail is called twice and that it was called with 'test+alias@other.com' at least once. As written, an implementation that uses the original email once and a transformed value the second time would still pass. To fully verify the intended behavior, consider asserting each call explicitly (for example, using toHaveBeenNthCalledWith for both calls, or checking the argument list of all invocations) so the test will fail if the wildcard query ever starts transforming the address for non-configured domains.

[dschom]

Do we need to actually use this routine in auth-server now to full fill the ticket?

[nshirley]

Do we need to actually use this routine in auth-server now to full fill the ticket?

I was looking and we're already using the new Bounce handler in auth-server. I think this will need to be uplifted before this weeks release

CC: @vbudhram & @dschom

[vbudhram]

@dschom Addressed feedback, copied the email-normalization logic to libs and the tests for coverage.