Thanks... the best I could get from the Sendmail site is that relay-domains is used to list domains I will relay mail for, but that access.db allows finer control... specifically of individual hosts, IP blocks, etc ??? Is this correct? Since you suggest using the access.db file, then what's the purpose of relay-domains?
Basically, here's what I need to do... let's say I have two offices and a co-lo. I want to relay for:
10.1.1. (office A)
192.168.1. (office B)
172.16.100. (local co-lo)
And just in case I want to put a valid DNS assigned host for my domain at my house, I want to relay for any valid hosts in my domain (confirmed by DNS)... so I als want to relay for:
Then I want to explicitly deny relay for all other hosts, IPs, etc. Do I have to list mydomain.com in relay-domains and the IP ranges for the offices in access.db? Or can I do it all in access.db?
Lastly... are the access and relay-domains files read top to bottom like a firewall ruleset so that if I list five relayed domains, then my last entry is 0.0.0.0 REJECT, will my IP ranges/domains be allowed to relay while everything else will reject?