{"action":"opened","issue":{"url":"https://api.github.com/repos/rails/rails/issues/21186","labels_url":"https://api.github.com/repos/rails/rails/issues/21186/labels{/name}","comments_url":"https://api.github.com/repos/rails/rails/issues/21186/comments","events_url":"https://api.github.com/repos/rails/rails/issues/21186/events","html_url":"https://github.com/rails/rails/issues/21186","id":100129934,"number":21186,"title":"ActionMailer's default subject doesn't use interpolation options","user":{"login":"fnando","id":3009,"avatar_url":"https://avatars.githubusercontent.com/u/3009?v=3","gravatar_id":"","url":"https://api.github.com/users/fnando","html_url":"https://github.com/fnando","followers_url":"https://api.github.com/users/fnando/followers","following_url":"https://api.github.com/users/fnando/following{/other_user}","gists_url":"https://api.github.com/users/fnando/gists{/gist_id}","starred_url":"https://api.github.com/users/fnando/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fnando/subscriptions","organizations_url":"https://api.github.com/users/fnando/orgs","repos_url":"https://api.github.com/users/fnando/repos","events_url":"https://api.github.com/users/fnando/events{/privacy}","received_events_url":"https://api.github.com/users/fnando/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-08-10T17:55:53Z","updated_at":"2015-08-10T17:55:53Z","closed_at":null,"body":"ActionMailer tries to retrieve subject from i18n. So if I have a `Mailer` class, it will look at `en.mailer.<mail name>.subject`. The documentation states that you can pass in interpolation options by setting `:interpolations`. The problem is that these options aren't used at all.\r\n\r\nHere's the line that calls `default_i18n_subject`: https://github.com/rails/rails/blob/6ac6daa43e1c5b7388f8fd69f8117eb7668887c7/actionmailer/lib/action_mailer/base.rb#L816\r\n\r\nAnd here's the line that define the method: https://github.com/rails/rails/blob/6ac6daa43e1c5b7388f8fd69f8117eb7668887c7/actionmailer/lib/action_mailer/base.rb#L879"}}