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cant send external email...

Dave Chamberlin
Trusted Contributor

cant send external email...

I am trying to send email beyond my domain. DNS is not enabled, nsswitch.conf has "files" only. I have in my hosts file the ip of our groupwise mail server. I have the sendmail.cf set with :
DLmydomain.com
DWmydomain.com
DS10.2.9.27 (the ip of the mailserver).

My internal emails (to mydomain) come through ok. Mail to name@otherdomain messages do not. When I do a sendmail -bv name@otherdomain, it shows that the mail is deliverable, through the groupwise mail server (relaying for my server is enabled on groupwise). When I send the message, it is returned with:
550 sender domain not found in DNS.
I don't understand WHO'S DNS cannot resolve my domain. We do a ping from anywhere in our domain, and the email server, and they resolve my server correctly.
Our groupwise admin says its a unix problem.
Can anyone give me some help?
Is this my problem or his problem?
7 REPLIES
someone_4
Honored Contributor

Re: cant send external email...

hello
is one of theese servers on a private network and one on a public network? Or both on a private network ? Are both unix boxes or are you trying to go from windows to unix or vice versa?

Richard
Sridhar Bhaskarla
Honored Contributor

Re: cant send external email...

I guess the servers on the remote domains are not able to resolve your domain successfully. Instead of sending from your domain, try sending mail to your domain from external sites like hotmail or yahoo to your address
like your_self@yourdomain.com and see if you are able to receive the mail.

-Sri
You may be disappointed if you fail, but you are doomed if you don't try
Printaporn_1
Esteemed Contributor

Re: cant send external email...

one requirement for sendmail version 8.8.6 up is you need to have a DNS in your environment.
and your DNS have to be able to resolve to the receiver domain.
enjoy any little thing in my life
Dave Chamberlin
Trusted Contributor

Re: cant send external email...

my server and the mail server are both on a private network. Our firewall connects us to the world. I have tried using DNS, but my local mail breaks when I do that.
Dave Chamberlin
Trusted Contributor

Re: cant send external email...

My server is unix, the mail server is a windows box.
Christopher Caldwell
Honored Contributor

Re: cant send external email...

My internal emails (to mydomain) come through ok. Mail to name@otherdomain messages do not. When I do a sendmail -bv name@otherdomain, it shows that the mail is deliverable, through the groupwise mail server (relaying for my server is enabled on groupwise). When I send the message, it is returned with:
550 sender domain not found in DNS.
I don't understand WHO'S DNS cannot resolve my domain. We do a ping from anywhere in our domain, and the email server, and they resolve my server correctly.
Our groupwise admin says its a unix problem.
Can anyone give me some help?
Is this my problem or his problem?

If you're using a private network inside your firewall (10.0.0.0/8) and you're connecting to external public mail servers, you should be getting NAT'd. Therefore, two things must happen for modern remote sendmail servers to accept your mail:
1) the external public IP address (the other side of the NAT) must be resolvable by external DNS servers.
2) your from address (joe@domain.com) must be resolvable in DNS. If you're using something like joe@internal.domain.com where the internal domain is only visible on the private network, external sendmail servers will probably reject your e-mail. To test for this problem, test an e-mail by doing something like
cat .profile | mailx -s "test e-mail" -f you@domain.com where domain.com can be resolved in DNS. If that's your problem, look at the DM macro, and set it to domain name that's resolvable in DNS.
Dave Chamberlin
Trusted Contributor

Re: cant send external email...

The curious part if this is I have a k200 on the same private network that works perfectly. I can send both internal and external emails. The /etc/host, sendmail.cf, nsswitch.conf and resolv.conf files have the same settings.