HES customers with outbound scanning enabled encounter issues when forwarding emails to Yahoo accounts. Clients receive the following NDR from HES:
From: Mail Delivery System [mailto:MAILER-DAEMON@relay.hes.trendmicro.com]
Subject: Undelivered Mail Returned to Sender
This is the mail system at host relay.hes.trendmicro.com. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.If you do so, please include this problem report. You can delete your own text from the attached returned message.
The mail system <firstname.lastname@example.org>: host j.mx.mail.yahoo.com[18.104.22.168] said: 554 Message not allowed -  (in reply to end of DATA command)
This rejection error is not caused by HES nor does the service contribute in causing this problem. Based on the error code description, MX.MAIL.YAHOO.COM is rejecting the email because the sending machine's time settings may be incorrect (i.e. it is set 1 month in advance). Yahoo will not accept emails with a "message not allowed" error.
To resolve the issue:
- Double-click the time on the right-bottom corner of the computer.
- Check for the correct day, month and time.
- Make the necessary changes and click OK.
- Once completed, send an email to someone with a Yahoo email address. The mail shold not be rejected anymore.
If the issue still occurs, contact Trend Micro Technical Support.