Mixed valid/invalid local recipients abort message instead of delivering valid recipients - General Info https://community.zextras.com/forum/general-info/mixed-valid-invalid-local-recipients-abort-message-instead-of-delivering-valid-recipients/ Zextras Community Discussion Board en-US Thu, 08 Oct 2026 10:54:43 +0000 wpForo 60 Mixed valid/invalid local recipients abort message instead of delivering valid recipients https://community.zextras.com/forum/general-info/mixed-valid-invalid-local-recipients-abort-message-instead-of-delivering-valid-recipients/#post-12621 Fri, 28 Aug 2026 11:59:22 +0000 Version: Carbonio Email Edition 26.6 on Ubuntu 24.04

Scenario:

Sender: meeting@example.com

Recipients: user1@example.com (valid) and user2@example.com (invalid)

Tested with Web Client, Outlook (EAS), Outlook (IMAP), Outlook (POP), Thunderbird.

Expected:

user1@example.com receives the mail.
Sender receives an NDR only for user2@example.com.

Actual:

Send fails (or Outlook(EAS) returns an NDR (with the email as attachment)). Email not found in Outbox or Sent Items
Valid recipient does not receive the original message.

Configuration:

zimbraMtaSmtpdRejectUnlistedRecipient=yes
smtpd_reject_unlisted_recipient=yes

Relevant log: 550 5.1.1 Recipient address rejected during RCPT processing.

Outlook POP/IMAP sends email to user1@example.com and gets NDR for user2
Carbonio webclient, Thunderbird not all sending that email saying that incorrect email (user2)

]]> General Info JupiterJKC https://community.zextras.com/forum/general-info/mixed-valid-invalid-local-recipients-abort-message-instead-of-delivering-valid-recipients/#post-12621