[KLUG Members] sendmail relaying question

[Peter Buxton]

On Fri, Nov 22, 2002 at 10:13:19AM -0500, bill wrote:

> It makes me think about relaying.  Not my computer, but the ISP.  It
> obviously isn't blocking ports, but is the ISP an open relay?

It isn't open if it's only relaying mail for its internal network and
designated customers.

> My sendmail box is set to prevent relaying (sending mail) from anybody
> but designated machines on my network.  But the sendmail box knows
> nothing about my ISP.  Should I somehow configure sendmail to say it
> is part of the ISP's network?

smarthost. Not necessarily necessary, but some ISP's will refuse mail
coming from dial-up lines that isn't forwarded through official
channels. (c.f. MAPS DUL) 

> I'm using a dynamic ip address with broadband (dsl), so if the e-mail
> is going out through my linux mail server, the ISP is just accepting
> it and sending it out.

A mail relay != standard packet delivery. The one is a transforming
server, the other is standard TCP/IP behavior.

-- 
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