Add support for the mail envelope from

[amanteaux]

To handle bounced emails with a dedicated email address, it is required to set the envelope from mail address: https://stackoverflow.com/questions/1782659/how-to-set-the-return-path-to-an-email-address-other-than-sender-address-using-j

Currently Simple Java Mail enables to set the SMTP parameter mail.smtp.from via the configuration of the Session of the Mailer.

It would be great if Simple Java Mail could:

• handle a property to manage the mail.smtp.from option directly (so users won't have to deal with the Session object),
• handle the "envelope from" property per mail (if the solution with SMTPMessage in the stackoverflow issue works: I have not tested it yet).

If that's ok, I can help implementing these features (and also test the solution with SMTPMessage).

[bbottema]

Isn't this the replyTo you are referring to?

[amanteaux]

Actually the replyTo enables to set an address that will be used when the recipient will answer the mail.
Whereas in the case of the mail envelope from field, the address will be used by MTA and SMTP servers to notify the sender that the email could not be sent.

Usually the default behavior is correct: we want the sender to be directly notified when an email could not be sent.
However, in some cases we want to be able to customize the address that will be used in the Return-Path header (that will be set by the SMTP server). In my current case, I want to use the Return-Path field for technical reasons: my client wants to use a special address for sending mails, but he cannot see the received emails in this address (big corporation, slow processes...) and he also wants to be notified when emails could not be sent.
But I think other people can benefit from this feature: you may want to have a nice email address to send mails and use a dedicated address like bounced@domain.com to automatically handle bounced back emails by a reporting software.

[bbottema]

It's also written that the from address should be filled by the receiving party, not the sending party. I'm still looking into it, but it's a little confusing.

[amanteaux]

It seems that this is the Return-Path header field that is filled by the receiving party.

However this field should be based on the mail envelope from value that is sent to the mail server before the mail object.

Currently I made some tests with Google accounts and non existing email providers: each time the SMTP server I am connecting to (a postfix server on my network, not the Google mail server) is notifying me on the correct address (not the one I sent the e-mail from).
Also the tests were currently only made with the mail.smtp.from parameter in the Session class.

[bbottema]

Excellent, I'll add it in this weekend. Thanks for the tests!

[amanteaux]

Thank you for your help!

If you want, I can also make a test with the SMTPMessage solution to set the mail envelope from value. This other solution would enable to use this feature per Mail instead of using it per Mailer.

[bbottema]

Currently working on these changes. Going to name it bounceToRecipient

email.setBounceToRecipient(..)
emailBuilder.bounceTo(..)

The JavaDoc will explain it will optionally set the Return-Path / Envelope FROM as a hint for the SMTP server to return bouncing emails to...

[amanteaux]

That sounds perfect, thank you!!