Hi folks,
My original problem was:
I got a mail from <root_at_royac5.rkk.hu> and we have no this name (and 
domain). I worried about hackers or pirates.
Well there's nothing to worry about. 
The problem was that royac5.astro.su.se's mail system was badly 
configured, and hadn't put the domain name in the mail header (from and 
reply to fields). A lot of people got the message like this:
from: (and reply to:) root_at_royac5.<one's domain name>.
So my mailer system without fully qualified hostname adds the
default domain name too, thinking it is local.
I received a lot of answers (more than 30).
Thanks for everyone.
I have to apologize to Wang Wei for I thought that he might pirate.
At first I was frightened.
Regards,
        Gyula Szemenyei
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|  Head of Computing Centre   |H-6000 Kecskemet, Rakoczi ut. 3|
| Centre for Regional Studies |P.O. Box 261.                  |
|Hungarian Academy of Sciences|Tel./Fax: (+36)-76-482-193     |
|          E-mail:szemgy_at_rkk.hu, postmaster_at_rkk.hu            |
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Received on Tue Nov 14 1995 - 18:08:51 NZDT