Jak poslat email na seznam

[Sasdad]

Kdyz chci poslat email prikazem:

sendmail From:sasdad na seznam.cz To:sasdad na seznam.cz Sender:sasdad na seznam.cz

Tak mi to vyhodi tohle:
Message 1:
>From root  Mon Apr 21 21:22:25 2003
Date: Mon, 21 Apr 2003 21:22:25 +0200
From: Mail Delivery Subsystem <MAILER-DAEMON na localhost.localdomain>
To: root na localhost.localdomain
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
        boundary="h3LJMPB13057.1050952945/localhost.localdomain"
Subject: Returned mail: see transcript for details
Auto-Submitted: auto-generated (failure)

This is a MIME-encapsulated message

--h3LJMPB13057.1050952945/localhost.localdomain

The original message was received at Mon, 21 Apr 2003 21:22:07 +0200
from root na localhost

   ----- The following addresses had permanent fatal errors -----
From:sasdad na seznam.cz
    (reason: 553 sorry, your envelope sender has been denied (#5.7.1))

   ----- Transcript of session follows -----
... while talking to mx2.seznam.cz.:
>>> RCPT To:<sasdad na seznam.cz>
<<< 553 sorry, your envelope sender has been denied (#5.7.1)
550 5.1.1 From:sasdad na seznam.cz... User unknown

--h3LJMPB13057.1050952945/localhost.localdomain
Content-Type: message/delivery-status

Reporting-MTA: dns; localhost.localdomain
Arrival-Date: Mon, 21 Apr 2003 21:22:07 +0200

Final-Recipient: RFC822; sasdad na seznam.cz
Action: failed
Status: 5.1.3
Remote-MTA: DNS; mx2.seznam.cz
Diagnostic-Code: SMTP; 553 sorry, your envelope sender has been denied (#5.7.1)
Last-Attempt-Date: Mon, 21 Apr 2003 21:22:25 +0200

--h3LJMPB13057.1050952945/localhost.localdomain
Content-Type: message/rfc822

Return-Path: <root>
Received: (from root na localhost)
        by localhost.localdomain (8.11.6/8.11.6) id h3LJM7C13029;
        Mon, 21 Apr 2003 21:22:07 +0200
Date: Mon, 21 Apr 2003 21:22:07 +0200
From: root <root>
Message-Id: <200304211922.h3LJM7C13029 na localhost.localdomain>


Co delam spatne? Nebo to ma Seznam nejak hlidane?