I created a new account with my name and administrator rights. Then I deleted the "admin@mydomain" account and added this address (admin@mydomain) as an alias to my account.

I can send mail from Zimbra and from the internet (GMail) to the admin@ alias. But if the Zimbra system itself tries to send an email to admin@ alias, the delivery fails without giving any reason. The notification of the failed delivery itself is delivered successfully to the account the admin@ alias belongs to.

This is the postfix notification mail (***** is from me to hide my domain name):
This is the Postfix program at host zimbra.*****.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 Postfix program

<admin@*****.com>: *****.com
The logfile doesn't tell my anything about the faild delivery, too (but about the successful delivered "undeliverable mail" information).

Any idea what happened and what I can do to creect this?

Thanks a lot