It seems there’s a bug in Symfony, when updating to Monolog Bundle 2.5.0 that causes this if you do not have the ‘spool’ config value set under the swiftmailer configuration.
I don’t know what to set in the spool config so that it doesn’t spool the emails, I don’t even know if this is possible at all. The way I do it is not set it.
However, now there’s this bug! Fortunately the way out is simple, we just have to add the services manually in one of our services files, as:
swiftmailer.transport.simplemailinvoker: class: Swift_Transport_SimpleMailInvoker swiftmailer.transport.eventdispatcher: class: Swift_Events_SimpleEventDispatcher swiftmailer.transport.real: class: Swift_Transport_MailTransport arguments: [@swiftmailer.transport.simplemailinvoker, @swiftmailer.transport.eventdispatcher]