Hi Yafar,
I see, did not recognize you were looking at the admin point of view and the smtp server.
If I add a “random” address like you mentioned before into my smtp settings, the login fails, whatever I type in.
I guess this just means that shopware tries to send the mail, but this fails so the login fails aswell.
Should not be a too big thing at the moment, if mailer is correct or you use “disable email delivery (temporarily)”, you are able to login again, however I added a ticket to our issue tracker for this: https://issues.shopware.com/issues/NEXT-7129
Kind regards,
Tim