Did you receive SPAM mail from xxxx@phys.chuo-u.ac.jp?
If you receive some SPAM mail from xxxx@phys.chuo-u.ac.jp (xxx can be substituted by any words), before complain us, please check mail header and see whether it includes lines like
Received: from ieyasu.phys.chuo-u.ac.jp (postfix@ieyasu.phys.chuo-u.ac.jp [133.91.80.1])
        by xxx.yyy.zzzz (8.9.3/3.7W-2.8compat) with ESMTP id PAA4679
        for ; Wed, 6 Dec 2000 15:42:21 +0900
Received: by ieyasu.phys.chuo-u.ac.jp (Postfix)
        id 2C4FD3F431; Wed,  6 Dec 2000 16:33:03 +0900 (JST).
If not, SPAM mail does not have any relation to our server. It is very easy to substitute ANY address to "From:" field. Actually speaking, you yourself can pretend to send e-mail from ANY e-mail address. Thanks.
Did you receive "Undelivered Mail Returned to Sender"?
Did you received some mail like
This is the Postfix program at host ieyasu.phys.chuo-u.ac.jp.

I'm sorry to have to inform you that the message returned
below could not be delivered to one or more destinations.

For further assistance, please contact 

If you do so, please include this problem report. You can
delete your own text from the message returned below.

                        The Postfix program

<decuoka52@phys.chuo-u.ac.jp>: unknown user: "decuoka52"
from our mail server? "decuoka52" may be different. We are not responsible for this. The reason is as follows:
Someone substitute our domain name "phys.chuo-u.ac.jp" into "From:" field included in some SPAM program. Probably, this SPAM program generate random name and attach it to "@phys.chuo-u.ac.jp", then send e-mails to addresses listed in some mail list provided for SPAMER. If this list include some e-mail address which respond to incoming e-mail, e.g., vacation which inform sender that receiver is absent, our mail server receive e-mails for non-existing address. Thus, our e-mail server try to reply to YOUR e-mail server to inform that this e-mail address does not exist. Actually speaking, it is rather difficult to stop sending such e-mails because it is in principle impossible to distinguish necessary error message from unnecessary error messages produced by SPAMER's e-mails. Please be patient for a while.
4 Jan. 2001