advice on anti-spam tools
jeffrey at goldmark.org
Thu Apr 5 18:48:52 UTC 2007
On Apr 4, 2007, at 4:25 PM, Gary Kline wrote:
> What I got caught on was "client," altho from the context,
> here ``client'' seems to mean the mail-server-sending-spam.'
> In the unix world, my server is the client--unless the
> client-server model is different with email.
Your mail server is constantly listening on port 25. When some other
process (typically on some other host) connects to the service you
are running on port 25, then the thing making the connection is the
client. Even if it is a full blown MTA.
Likewise when your mail server wants to pass mail on to some other
server your server initiates a connection with a destination port
(typically) of 25. During that activity your MTA is acting as a client.
For mail the terms client and server have the usual unix meaning,
it's just that most things that act as SMTP servers (sendmail,
postfix, etc, etc) also act as SMTP clients. But note that this
isn't the case the other way around. Many things that act as SMTP
clients (pine, mutt, thunderbird, Outhouse) do NOT act as SMTP servers.
I guess what might be confusing here is that it is typically to
client that sends the most information during an SMTP session. With
HTTP it is the other way around. But think instead of doing
uploading with FTP. The client sends most of the information.
I hope this helps.
Jeffrey Goldberg http://www.goldmark.org/jeff/
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