I believe this is the migration you are looking for https://github.com/bodrovis/SitePoint-Mailboxer/blob/master/db/migrate/20141208140641_create_mailboxer.mailboxer_engine.rb#L23 (just alter it after running rails g mailboxer:install).
I believe this is the migration you are looking for https://github.com/bodrovis/SitePoint-Mailboxer/blob/master/db/migrate/20141208140641_create_mailboxer.mailboxer_engine.rb#L23 (just alter it after running rails g mailboxer:install).