[KLUG Members] sendmail relaying question

[bill]

Trying to master sendmail, I've set it up to handle outgoing mail for a home
network.  Seems to work fine.  Now I'm wondering how.

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?

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?

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.  Does that mean they are technically an open relay?  Or is sendmail
locating the destination pop3 server and doing negotiations directly?

kind regards,

bill hollett