create smtp authentication route with haproxy

Question

Is it possible to insert username and authentication password in the haproxy route towards an smtp with authentication?

now I have a route like:

frontend SMTP bind *:25 mode tcp default_backend smtp backend smtp balance roundrobin mode tcp server vm3 smtp.domain.global:25 check

calling the route with a java job: com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.3 Client was not authenticated

it is difficult for me to modify the java job now, while I would like to modify the haproxy configuration

Answer 1

As the pasted config looks a little bit odd let me format it.

frontend SMTP
  bind *:25
  mode tcp
  default_backend smtp

backend smtp 
  balance roundrobin
  mode tcp
  server vm3 smtp.domain.global:25 check

Hope this makes now clear why it's not possible.
HAProxy does not handle the SMTP Protocol, it just forwards the connection via TCP to the mail server therefore can't the SMTP Auth be injected nor done by HAProxy.