What is the Email sender? (MAIL FROM, Envelop Sender, Bounce Address)

About

The sender is an envelope email address (mailbox) that:

• indicates where the message came from
• receives problems delivering the message (Undeliverable message notices/bounce)
• is set during a SMTP transaction by the MAIL FROM command
• is not seen by message recipients (final users)

The sender is also known as:

• the return path
• the mail from address
• the bounce address

Sender vs Author (From:)

The value is generally the author (ie the address in the from header) but in other cases such as a mailing list, it may be not.

Example

• For a mailing list, it can be a bounce email with or without a tag (ie +)

[email protected]

• For a single send, it can be the user

[email protected]

Return-Path Header

If there are multiple relays, the original sender can be found in the Return-Path header.

Sender Policy

In a SMTP transaction, the sender should conform to the Sender Policy Framework (SPF)

Library

Java

You set the bounce with the mail.smtp.host property

Properties props = new Properties();
props.put("mail.smtp.host", "my-mail-server");
Session session = Session.getInstance(props, null);

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