Automatic replies, NDR and return path
This article explains how the recipient's email server determines where to redirect different reply types and bounced emails.
Understanding email headers
The email header is a code snippet in an HTML email, that contains information about the sender, recipient, email’s route to the inbox and various authentication details. The recipient's email server also uses email header metadata to determine where to redirect replies and bounced emails. As a sender, you can specify the following reply-related email headers:
- From (controlled by JungleMail),
- Reply-To (controlled by JungleMail),
- Return-Path (generated by your SMTP server).
Note that the recipient's email server may be configured to behave differently than you expect. For example, the Exchange server does not send duplicate automatic replies (it suppresses duplicate emails for one day) or automatic replies to yourself.
When you send a newsletter to a subscriber and they click "Reply", the reply message is typically sent to the email address listed in the From header. However, if you specify the Reply-To address, this address is used instead.
Automatic out-of-office replies are typically sent to the From address, not the Reply-To or Return-Path address. You can also use additional headers to suppress automatic replies (or at least indicate the recipient's server that you don’t want them). This feature is available in JungleMail 7.3.20.01272 or later version.
Non-delivery reports (NDR), or messages about bounced emails, are sent to the Return-Path address.