Ow Mun Heng wrote: > Is this correct behaviour? I thought that to send emails you need to > either be authenticated (SMTP auth) or be on the same IPs as your > ISP?? > > Or is this what's happening? Sendmail is actually querying DNS root > servers and then upon getting the MX server, it connects straight to > port 25 of that MX Server and sends it? If that's the case, what's > stopping it from being a relay??? > > /curious By default, redhat configures sendmail (actually sendmail.mc) to only accept smtp requests from localhost. You would have to override that setting to have sendmail accept smtp requests from other hosts on your LAN. The maillog entry prior to the one you posted should show where the e-mail in question was submitted from. Based on your post where you stated you have NOT modified sendmail.mc, I'd be willing to bet it was submitted from localhost. Take a look! As for your concern about being an open-relay... even if you were to modify sendmail.mc and allow sendmail to accept smtp connections from another host on your LAN, there are some additional settings that define exactly what can be relayed. These settings are usually defined in /etc/mail/access with the RELAY statement. Again, by default only localhost is allowed to relay. Further reading should include /usr/share/sendmail-mc/README. Search for the keywords "relay" and "access_db". Steve Cowles
