We are sending email using smtp port 25 in a local Exchange 2010 server We do not set username nor passwords in the SMTP connection, only "form" address. Mails are sent to external recipients after the Exchange enabled our server as an anonymous mail source.
However when the recipient does not exists the sender (the mail in the from: field of the mail header) doesn't get an NDR to his mailbox.
When trying to send email to the same recipient from outlook using native exchange protocol the sender get NDR to his mailbox.
Is it possible to enable the sender to receive NDR when sending emails to external address with SMTP Port 25 anonymously (however the "from" field has a valid email in it) ?
If not what is the best practice to accomplish it, considering we send email using SMTP on port 25 with no SSL