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)