Correcting Sendmail warning that a local address may be forged
Posted on 2006-07-09
I have purchased a fixed IP from a local ISP in Alaska, but my sendmail server is located in Michigan on a /29 network behind a NAT'd firewall. By adding a relay for the Alaska IP in /etc/mail/access.db, I'm able to use my pop3 mail client in Alaska to download mail from Michigan, which is great. However, I get this warning in my maillog:
Jul 9 03:39:47 myhost sendmail: k697dk7k017036: from=<email@example.com>, size=337, class=0, nrcpts=1, msgid=<firstname.lastname@example.org>, proto=SMTP, daemon=MTA, relay=1-2-3-4-dsl-rb1.acsalaska.net [18.104.22.168] (may be forged)
To get rid of the (may be forged) warning, I added this entry to /etc/mail/relay-domains:
But that didn't help. I'm registered with Network Solutions, but I don't list routable IPs there that aren't associated with hosting a service, so I'm not sure what to do. I plan to keep the IP in Alaska (because we're moving there) and transition my network from Michigan to Alaska. I understand that the problem is caused by reverse DNS not matching the forward lookup, but the solution to this isn't apparent. I've seen the same error in Michigan when I implemented DHCP - since my client host name(s) could no longer be associated with a fixed IP, I removed the A records and started seeing may-be-forged errors in the maillog. Have read all I can find on how to use the access db to fix this, but no cigar. The solutions may be different, but in any event I need help. Thanks in advance.