If you still get following error (Failed to authenticate on SMTP server with username) when sending email please follow below steps.
Swift_TransportException
Failed to authenticate on SMTP server with username “yourid@gmail.com” using 3 possible authenticators. Authenticator LOGIN returned Expected response code 235 but got code “535”, with message “535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8 https://support.google.com/mail/?p=BadCredentials c17-20020a170902d49100b001624cd63bbbsm4334145plg.133 – gsmtp “. Authenticator PLAIN returned Expected response code 235 but got code “535”, with message “535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8 https://support.google.com/mail/?p=BadCredentials c17-20020a170902d49100b001624cd63bbbsm4334145plg.133 – gsmtp “. Authenticator XOAUTH2 returned Expected response code 250 but got code “535”, with message “535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8 https://support.google.com/mail/?p=BadCredentials c17-20020a170902d49100b001624cd63bbbsm4334145plg.133 – gsmtp “.
Step 1:
Please login into your gmail account and click on “Manage your Google Account” button form right to your profile picture.

Step 2:
Go to to Security tab form left menu and please turn on 2-Step Verification by using your Recovery Phone.

Step 3:
Click on App Password bar form Sign in to Google section.

Step 4:
Select the app and device you want to generate the app password for. And enter a platform name and click on GENERATE button to generate new password.

Finally copy your new generated password and save it your self also use it to your other device or app where you want to send SMTP email.
Step 5:
Now change password on Laravel .env file MAIL_PASSWORD value with new generated password.
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