Sourced from actionmailer's releases.

8.1.0

Active Support

• Remove deprecated passing a Time object to Time#since.

  Rafael Mendonça França

• Remove deprecated Benchmark.ms method. It is now defined in the benchmark gem.

  Rafael Mendonça França

• Remove deprecated addition for Time instances with ActiveSupport::TimeWithZone.

  Rafael Mendonça França

• Remove deprecated support for to_time to preserve the system local time. It will now always preserve the receiver timezone.

  Rafael Mendonça França

• Deprecate config.active_support.to_time_preserves_timezone.

  Rafael Mendonça França

• Standardize event name formatting in assert_event_reported error messages.

  The event name in failure messages now uses .inspect (e.g., name: "user.created") to match assert_events_reported and provide type clarity between strings and symbols. This only affects tests that assert on the failure message format itself.

  George Ma

• Fix Enumerable#sole to return the full tuple instead of just the first element of the tuple.

  Olivier Bellone

• Fix parallel tests hanging when worker processes die abruptly.

  Previously, if a worker process was killed (e.g., OOM killed, kill -9) during parallel test execution, the test suite would hang forever waiting for the dead worker.

  Joshua Young

• Add config.active_support.escape_js_separators_in_json.

  Introduce a new framework default to skip escaping LINE SEPARATOR (U+2028) and PARAGRAPH SEPARATOR (U+2029) in JSON.

  Historically these characters were not valid inside JavaScript literal strings but that changed in ECMAScript 2019. As such it's no longer a concern in modern browsers: https://caniuse.com/mdn-javascript_builtins_json_json_superset.

... (truncated)

Sourced from actionmailer's changelog.

Rails 8.1.0 (October 22, 2025)

• Add structured events for Action Mailer:

  • action_mailer.delivered
  • action_mailer.processed

  Gannon McGibbon

• Add deliver_all_later to enqueue multiple emails at once.

  user_emails = User.all.map { |user| Notifier.welcome(user) }
  ActionMailer.deliver_all_later(user_emails)
  use a custom queue
  ActionMailer.deliver_all_later(user_emails, queue: :my_queue)

  This can greatly reduce the number of round-trips to the queue datastore. For queue adapters that do not implement the enqueue_all method, we fall back to enqueuing email jobs indvidually.

  fatkodima

Please check 8-0-stable for previous changes.

• 1cdd190 Preparing for 8.1.0 release
• 1ace683 Preparing for 8.1.0.rc1 release
• d6f9f62 Make the Structured Event Subscriber emit events in format that are useful fo...
• d2518fa Merge pull request #55748 from Shopify/event_with_debug_helper
• 1e77699 Make all framework log subscribers API private
• 78857a3 Introduce with_debug_event_reporting to enable event reporter debug mode
• ebb01c5 Emit only one structured event per notification event
• 6f26cc8 Add method silencing support for debug events
• a486b99 Structured events for Action Mailer
• 1797261 Add missing test when an array is passed to
• Additional commits viewable in compare view

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