That's because they put your actual address (and those of other victms) in the BCC: field.
telnet localhost 25
Connected to localhost.localdomain.
Escape character is '^]'.
220 localhost.localdomain ESMTP Sendmail 8.13.4/8.13.4/Debian-3sarge1; Tue, 28 Mar 2006 18:46:07 +0100; (No UCE/UBE) logging access from: localhost.localdomain(OK)-localhost.localdomain [127.0.0.1]
250 localhost.localdomain Hello localhost.localdomain [127.0.0.1], pleased to meet you
MAIL FROM: test@localhost
250 2.1.0 test@localhost... Sender ok
RCPT TO: cjll@localhost
250 2.1.5 cjll@localhost... Recipient ok
354 Enter mail, end with "." on a line by itself
To: Fred Bloggs <email@example.com>
From: Leet Haxor <firstname.lastname@example.org>
Subject: This is fun
This haxoring is fun!
250 2.0.0 k2SHk7m8005877 Message accepted for delivery
221 2.0.0 localhost.localdomain closing connection
Connection closed by foreign host.
nelz wrote:Limnits on the lengths of headers mean Bcc: can only be used to send to a fairly small number of addresses, whereas listing then in the SMTP envelope is limited only by the mail server (some have limits to prevent their being used for spam).
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