title: Symfony 5.3 Mailer setup env vars not reading correctly
body: <p>In a Symfony 5.3 project I am using the Mailer (..\Symfony\Component\Mailer\MailerInterface) to send mails.
  For devolopment I required &quot;symfony/google-mailer&quot; with composer and set it up in .env.local.
  Say username is &quot;example@gmail.com&quot; and password is &quot;0000&quot;.</p>
  <p>In .env.local I specified</p>
  <pre><code>MAILER_USER='example@gmail.com'
  MAILER_PASSWORD='0000'
  
  MAILER_DSN=gmail://MAILER_USER:MAILER_PASSWORD@default
  </code></pre>
  <p>which results in error</p>
  <pre><code>Failed to authenticate on SMTP server with username &quot;MAILER_USER&quot; using the following authenticators: &quot;LOGIN&quot;, &quot;PLAIN&quot;, &quot;XOAUTH2&quot;. Authenticator &quot;LOGIN&quot; returned &quot;Symfony\Component\Mailer\Exception\TransportException: Expected response code &quot;235&quot; but got code &quot;535&quot;, with message &quot;535-5.7.8 Username and Password not accepted.
  </code></pre>
  <p>As stated in the docs I changed the one special character in user name (&quot;@&quot;) to it's URL-encoded form like</p>
  <pre><code>MAILER_USER='example%40gmail.com'
  </code></pre>
  <p>which then results in the error</p>
  <pre><code>Email &quot;example%40gmail.com&quot; does not comply with addr-spec of RFC 2822.
  </code></pre>
  <p>(Obviously the URL-encoding didn't work like expected (because it wasn't reversed?))
  I tried to load the env vars in paramaters in services.yaml and use the parameters instead - but that lead to the first error too.</p>
  <p>If I write the auth infos into the MAILER_DSN env var directly it just works fine without problems, like</p>
  <pre><code>MAILER_DSN=gmail://example@gmail.com:0000@default
  </code></pre>
  <p>So this seems to be a syntax problem which I can't figure out from the docs.
  Any hints?</p>