Symfony 4上的Swiftmailer - fwrite（）警告

Question

I am testing my Symfony 4 app and I configured my .env file like this:

MAILER_URL=smtp://mail.something.com:465?encryption=ssl&auth_mode=login&username=[e-mail]&password=ABCDEFGH&encryption=ssl

In command prompt I have used standard mail testing command:

php bin/console swiftmailer:email:send

but I've got an error:

[OK] 1 emails were successfully sent.

In StreamBuffer.php line 231: Warning: fwrite(): SSL: Operacja ukoczona pomylnie.

which can be translated to "Operation completed successfully" (I'm using polish Windows 10).

Email was not sent. Does anyone have an idea how to solve this problem?