symfony2.3 spool monolog error email in command - email

Question

I know that this question was already made in this post: Send email when error occurs in console command of Symfony2 app, but answers do not provide a complete solution to the problem at hand and I can't comment on original post.
I need to send a monolog error email in command. E-mail is correctly enqueued in a file spooler; unfortunately I'm forced to use a memory spool.
Strangely enough the code snipper provided to manually flush the spool does work for emails generated in my code, not for monolog.
Does anybody know why this is happening and wether it would be possible to use a memory spool?
config.yml:
# Swiftmailer Configuration
swiftmailer:
transport: %mailer_transport%
host: %mailer_host%
username: %mailer_user%
password: %mailer_password%
spool: { type: memory }
# Monolog Configuration
monolog:
channels: ["account.create"]
handlers:
account.create.group:
type: group
members: [account.create.streamed, account.create.buffered]
channels: [account.create]
account.create.streamed:
type: stream
path: %kernel.logs_dir%/accounts_creation.log
level: info
account.create.buffered:
type: buffer
handler: account.create.swift
account.create.swift:
type: swift_mailer
from_email: xxx#yyy.com
to_email: aaa#gmail.com
subject: 'An Error Occurred while managing zzz!'
level: critical
config_prod.yml:
monolog:
handlers:
main:
type: fingers_crossed
action_level: error
handler: nested
nested:
type: stream
path: %kernel.logs_dir%/%kernel.environment%.log
level: debug
channels: [!account.create]
usage example:
try
{
//code that could block
}
catch(ManageUserBlockingExceptionInterface $e)
{
$exitCode = self::EXIT_CODE_ERROR_BLOCKING;
//le eccezioni bloccanti vengono loggate e non si conferma che
//il messaggio è stato utilizzato ma si termina la coda
if(!\is_null($this->logger))
{
$this->logger->crit($e->getMessage());
}
}
the logger is injected in service by dependency injection as a service:
...
<argument type="service" id="monolog.logger.account.create" on-invalid="null" />
...
and it works because critical errors are streamed in file log; but also email is created if swiftmailer is configured with a file spool.
Finally, the code to manually flush memory spool is as folllow:
protected function flushMailSpool()
{
$mailer = $this->container->get('mailer');
$spool = $mailer->getTransport()->getSpool();
$transport = $this->container->get('swiftmailer.transport.real');
$spool->flushQueue($transport);
}
it is called immediately after a service purposedly sends an email; I noticed that the same code, put in command and adapted to command environment i.e. $this->container becomes $this->getContainer() does not work, maybe due to a scope change?