I have set my hostname in multiple files and also configured my "domain" name (this is all behind a router, so not public on the net). Every day I get a mailgram from logwatch which is part right and part wrong. The "sender" is: "logwatch@ c13-ss-2-lb.cnet.com" but the subject is " Logwatch for rainbow (Linux)". The subject is right - I am on host rainbow in rainbowapps.com. I have looked in many places but cannot find where "c13-ss-2-lb.cnet.com" is coming from. Where does this name get configures?

As root, run 'sendmail -bv postmaster@rainbowapps.com.com' or 'dig any com.com' and there you have it.

When I run "sendmail -bv ..." I get back the name I am seeing in the email, as you predicted.

Does this mean that the REAL public owner of this IP I am using behind a firewall is the name I am seeing AND I must just ignore the poor name?

Or

Can I fix this name in the sendmail file (I have looked and cannot see where to fix)?

I would prefer to fix it, but can understand if it is picking up the real owner of this IP address and thinks I am confused here.

The basis is that any PTR for any DN ending in a ".com.com" gets resolved to "c13-ss-2-lb.cnet.com", and since you didn't post your DN details it could be you chose your LAN domainname badly or the "from" address was misconfigured somewhere.

hmmm - pardon my ignorance here. what do I need to post about my DN service? and where do I find where my 'from" line is configured.

I have looked at sendmail.cf and see nothing here. when I type domainname I get nothing - perhaps that is the problem (hostname is right).

I am looking to find the answer here - what can I do to give you better information?

Did you chose some IP range for your LAN that actually is routable?
Did you choose a domainname for your LAN that resolves externally to something".com.com"?

1) my lan uses static IP's all behind a router firewall. Internally I am 192-168.101.nnn and externally whatever the cable modem + router assigns. I use fixed addresses and IPV4 as I have a couple old Sun boxes which I don't need to upgrade with this new Linux box here. The fourth part of the address is 1 for the router and between 2 and 150 for 2 net printers, a PC, 2 suns and a Mac. I know the maximum is 255 and so everyone "internally" works and can find each other.
- so I believe everything is routable and have no problems except sendmail locally

2) I did not set a domainname (get "(none)" to `domainname` command). I could use the old one I had "rainbowapps.com" but don't see where to set it. After your original post, I did change /etc/sysconfig/network to have my hostname as rainbow.rainbowapps.com and rebooted (was localhost.localdomain), but I still get "(none)" to a domainname command. I don't see a /etc/domainname file, something which existed in Solaris and I knew to set.

I have looked at other Linux machines which are almost identical and see nothing really different. The only major difference is that these machines have a registered static IP (with godaddy) so they really do have a "legal" sendmail. I don't expect that I can use sendmail externally unless I register as static IP but I think it should work inside this local net to this host. In fact it works fine with messages showing me with a From line of "ray@rainbow.rainbowapps.com" or root@rainbow.rainbowapps.com depending on who sends the local mail. So this problem mail arrives to me via the local "/etc/aliases" which mails to an alias on one of the three static IP Linux boxes where it then posts again by alias to yahoo. It appears that the other box sees me as coming from com.com. I am attempting to have all my mail go one place so I don't have to read it locally and on the web. Maybe this problem is because of this other machine pass through. I cannot mail directly to yahoo as I don't have a real registered address and they would think it was spam.

Finally I am not using YP or NIS - I guess I could but don't see any good reason to do so. If you advise me to bring up NIS, I guess I could try. They both seem like overkill to me.

No, you use "dnsdomainname" to check that. And I think you should not use registered(?) domainnames for your LAN unless you make sure nothing in your LAN can resolve it to something on the outside meaning to something you don't own or don't have access to...


And there you have it. Good you traced it down to that. Does resolving the static IP of your MTA give any clues?


Well, you have static IPs. Does your hosting provider allow those IP addresses to use its MTA as smarthost?


No, it luckily has nothing to do with that.

Hmmm - you lost me there - I am unfamiliar with MTA (unless you live in Boston)

So I am not sure what you think I should do. I have static IPs only within this little local net and my router/firewall is my gateway. I use DNS from my cable provider. The local boxes, printers, and gateway are all defined in /etc/hosts as well as the DNS and secondary DNS servers.

"Does resolving the static IP of your MTA give any clues?"

How do I do that?

"Does your hosting provider allow those IP addresses to use its MTA as smarthost?"

I am not sure how to ask that question. I am not currently using a "hosting" provider or I don't think I am. I used to host a website on godaddy, but currently just have a couple domain names there - no more hosting. Other than that, I am connected by cable modem service thru Time Warner.

I probably could get GoDaddy to provide what you are talking about for a fee. I don't know how to ask for it and would need to evaluate if it is worth it. I am only working on sweat equity projects right now.

Sorry for that. I'll try to cut things short and avoid using Three Letter Acronyms. Since you have an account with a cable provider, can't you use your cable providers mailserver (aka MTA, usually found at addresses like "smtp.yourprovid.er" or "mail.yourprovid.er") to send e-mail? In Sendmail that would be accomplished by setting the "smarthost" directive.

Thanks I will pursue that avenue with the cable provider. By the way I am really tired of 3 and 4 letter acronyms, they grow tiresome - I was an IBM systems programmer when I was young and foolish. SO - TLA means time of last access. :=]

OK, I have worked with my ISP to get evolution working and it does. I can send and receive mail. Let us say the smtp outgoing address name is
smtp.fu.bar

I have researched sendmail.cf (no man page available) and searched thru the file via grep for smarthost. I see lots of lines that I should not muck with and one I might:

FallbackSmartHost=fall.back.host.net

1) Should I modify the above line to match the smtlp.fu.bar name?
2) Should I add one more entry before that line? - e.g???

smarthost=smtp.fu.bar

3) Or do I do this in the /etc/aliases file and if so - is this right?
smarthost smtp.fu.bar # or is it SmartHost

with a TAB, of course not several spaces.

It looks like I am close to resolving this with your excellent advice. I hope I don't have to buy commercial service from the provider to do this (if so, I will live with the ridiculous name).

And finally do i need to reboot or can I "kill -1 pid.of.smtp"?