Sendmail doesn't send mail to outside my domain

I use sendmail to send mails. I am not able to send mail to domains other than mine . i.e if I try sending a mail to yahoo account , it doesn't go but it can recieve from yahoo domain. I am very new to all these and I don';t know how can I make it work. This is very improtant to me as I have a webserver running and I need to send mails to lot of people in other domains regularly. I was always assuming that my mails are reaching them but recently got to know it's not. Please help me.
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what Opearting system u are using.
do u have relay server.
This is for Linux.
if yes then u can add relay ip address to

add ip addresses to /etc/mail/access
Just insert a new line such as:  RELAY  (to relay from one machine)
or  RELAY (to relay from the whole subnet)
AchiveeAuthor Commented:
I am using MAndrake Linux 9.1 and I don't know anything about relay server. I am very new to this field. Kindly help me configuring this.
I use kmail for other purposes and it uses smtp to send mails on the port 25 and if I send throguh this, mails are recieved at the other end in my case  recieve at yahoo account
If I use sendmail through commandline and give
I don't recieve any
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AchiveeAuthor Commented:
My /etc/mail/access file has below lines.
# by default we allow relaying from localhost...
localhost.localdomain       RELAY
localhost           RELAY           RELAY

Does this help
edit your

# "Smart" relay host (may be null)

edit it to:
# "Smart" relay host (may be null)
whereby mail.your-provider.domain is the smtp-host you normally use when sending email directly out of an e-mail client.

after editing just restart sendmail and everything should be fine...
set the relay to your smtp host so that all emails not in your domain can be relayed to the net
AchiveeAuthor Commented:
Thank you very much Shiv
It's working now. DS was null initially.
great! now can you please accept shiv's answer and close the question.
Good to know you got the issue resolved. You can close the question by following this guidelines:
the question is answered.

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