We get an exception
javax.mail.AuthenticationFailedException: 535 5.7.0 authentication failed

It looks like the application try to do an authentication on the SMTP server. Note that in the configuration there is no user or password define (no authentication)
Find in attachments the logs of the SMTP server +
Note that in an SMTP authentification, login & passwords are encoded in base 64, so we get:

$ echo "VXNlcm5hbWU6" | base64 -d
Username:laurent

$ echo "UGFzc3dvcmQ6" | base64 -d
Password:laurent