Logback SMTPAppender not sending email

I also faced this issue and found the solution. To run the above code, you have to make some changes in your configuration:

1. Add <STARTTLS>true</STARTTLS>
2. Add <asynchronousSending>false</asynchronousSending>

It seems to have been an issue with the SMTP server I was using. I setup Papercut as a local smtp server and I can see it receive the messages