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Sendmail through DNS?

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Super Advisor

Sendmail through DNS?

Hello Guruz,

There is a mailserver with IPrange, i could able to resolve it through DNS,

Its resolving.

But not pinging, port 25 is open for mailserver IP.

But when i am sending mail, i am geting the below error

dsn=x.x.x, stat=Host unknown (Name server: host not found)

Could some one tell me how to configure sendmail through DNS?
Honored Contributor

Re: Sendmail through DNS?

> Name server: host not found

This says that your server that sent the email, can not resolve the host that is supposed to receive the mail.

Is the receiving host outside your network (internet) and can your sending server resolve internet hosts? In most cases you use a relay server to send emails and a different set up is required.
Mel Burslan
Honored Contributor

Re: Sendmail through DNS?

grep "^DS" /etc/mail/

what does the output look like ?

if it comes back as


or no output at all, it is assumed that your server is directly attached to the internet (not a wise thing and most probably is not the case) and relaying mail messages to the other hosts on its own, without the help of a relay server. Is this the case ?
UNIX because I majored in cryptology...
Michael Steele_2
Honored Contributor

Re: Sendmail through DNS?


Had the same problem when we migrated from one network to another, for example 192.1 and 15.1. And sendmail failed with the same errors until we updated the server with a 15.1 DNS (* nameserver *).
Support Fatherhood - Stop Family Law
Super Advisor

Re: Sendmail through DNS?

Thanks all.