Add comprehensive email validation for blocked users

[ShashankFC]

Test 3

Summary by CodeRabbit

Release Notes

New Features

• Added email blocking mechanism for account creation that prevents specific email addresses from being used
• Enhanced email validation to track and reject previously failed emails
• Improved account creation error responses with detailed validation information

Database

• New database table added to persist blocked email configurations and tracking data

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Replicated from ai-code-review-evaluation/discourse-coderabbit#3

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Note

Medium Risk
Touches account creation and email validation paths and adds a new database-backed blocking mechanism; misconfiguration or validator bugs could prevent legitimate signups.

Overview
Adds a persistent blocked email system: introduces BlockedEmail + migration and an EmailValidator that enforces domain allow/deny lists and blocks specific emails while tracking match statistics.

Updates User to use the new email: true validator and extends UsersController#create failure responses to include structured errors and submitted values. The signup modal (CreateAccountController) now remembers rejected emails from the server and marks them invalid on subsequent attempts without re-submitting.

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[ShashankFC]

bugbot run

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Validation side-effect causes double match_count increment

Medium Severity

BlockedEmail.should_block? has a database write side-effect (incrementing match_count and calling save) but is invoked from within a validator. In users_controller.rb#create, user.valid? on line 168 triggers validations (including EmailValidator → should_block?), and then user.save on line 172 re-runs all validations, calling should_block? a second time. This causes match_count to be incremented by 2 for every single account creation attempt with a blocked email, producing inaccurate tracking data.

Additional Locations (1)

• lib/validators/email_validator.rb#L12-L15