Updating Laravel Mail Config at Runtime

For the project I am working on we want to have multiple SMTP configurations in the database, which can be chosen at runtime. It's very easy to update the mail config using the config() helper, but for some reason that did not change the SMTP settings used to actually send the mail. I did a lot of research and found some answers for older versions of Laravel that did not work with 5.4.

Eventually I was able to find how to accomplish this from this post on Laravel.io. It seems that the mailer instance is created with the app, so updating the config won't change the properties of it which have already been set. To do that you need to use the following code:

extract(config('mail'));

$transport = \Swift_SmtpTransport::newInstance($host, $port);
// set encryption
if (isset($encryption)) $transport->setEncryption($encryption);
// set username and password
if (isset($username))
{
    $transport->setUsername($username);
    $transport->setPassword($password);
}

// set new swift mailer
Mail::setSwiftMailer(new \Swift_Mailer($transport));
// set from name and address
if (is_array($from) && isset($from['address']))
{
    Mail::alwaysFrom($from['address'], $from['name']);
}

If you execute this after you have updated the config it will create a new instance of swift_mailer with the update mail config. Once that is done you can just send the mails and it will use the proper SMTP server.