RMM (Reply Mail Management) - Auto OOO/Vacation Mode Replies Not Received by RMM servers for Emails Sent from Marketing Cloud Gmail/Yahoo

When using email clients such as Gmail and Yahoo with Auto Out-of-Office (OOO) or Vacation mode enabled, the auto-reply messages may not be received for emails sent from Marketing Cloud. This issue arises because Gmail and Yahoo send auto-response (vacation) replies to the Return-Path header instead of the Reply-To header. This behaviour is in line with the option provided by RFC 3834 - Recommendations for Automatic Responses to Electronic Mail (https://datatracker.ietf.org/doc/html/rfc3834#section-4). However, this causes problems for Remote Monitoring and Management (RMM) servers, as they expect out-of-office messages to be sent to the Reply-To header. Additionally, Gmail and Yahoo treat the Return Path as a bounce message, resulting in the auto-reply not being forwarded to the RMM server.
 

Issue Reproduction Steps:

• Enable vacation mode/OOO in a Gmail or Yahoo account.
• Create a sender profile in SFMC by choosing Specified information and entering From Name and From Address fields and make sure to have a Valid Physical inbox for the From Address
• Send an email from SFMC to the Gmail or Yahoo account using an RMM without auto-discarding out-of-office messages.
• Observe that the auto-response from the vacation message is not received

Cause:

Gmail and Yahoo send auto-response (vacation) replies to the Return-Path header instead of the Reply-To header. This behaviour aligns with the option specified in RFC 3834, which allows for the auto-OOO replies to be sent to the Return-Path address. However, this approach prevents the auto-replies from being forwarded through RMM servers as they expect out-of-office messages in the Reply-To header.

See Also:
Out of Office messages from Outlook not filtered by Reply Mail Management