sendmail server unable to receive external mail
 

Hi,

I've set up sendmail server with the domain name, say
linux4u.com.

and I edit the sendmail.mc file

dnl # define(`UUCP_MAILER_MAX', `2000000')dnl
dnl # DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
dnl # FEATURE(`accept_unresolvable_domains')dnl
LOCAL_DOMAIN(`linux4u.com')dnl
MASQUERADE_AS(`linux4u.com')dnl


and "m4"

I can receive mail from root to user@linux4u.com.
and send mail to my external mailbox e.g gmail.

However, I cannot receive email sending from external mailbox.
e.g. gmail to user@linux4u.com

Why? kindly advise.

It's a long while since I used sendmail but:

The address you are using i.e smtp.linux4u.com resolves to your external ip address?

You have port 25 open in your firewall ?

Your firewall is routing traffic sent to port 25 to the local address 127.0.0.1 as it looks as though sendmail is only listening on 127.0.0.1 and not your external ip address.

Hi,

Thanks you.

yap... you are right, this is because of firewall protection.

However, I'm no the firewall guy. Someone have "force" the ip address
to point to correct one.... this is what I heard.
Please correct me if I wrong.

I expected, the mail should able to deliver .... and take time to route.
As until now I didn't receive any "Mail Delivery Subsystem" from
mailer-daemon@gmail.com.

Thank you again.

Regards,
:newbie:

it depends on how your mail server connects to the internet. in most cases, it will be on a local network behind a firewall and connect to the outside world through a gateway (in my case a simple linksys router). your external IP address will then point to that gateway, and anyone requesting to open a connection on port 25 with your IP address will be talking to the gateway and not your mail server (which is actually 192.169.1.120 or whatever). so you need to set up port forwarding for port 25. in my case it was as simple as logging into my router and entering a couple numbers. it depends on how your network is set up.

Hi,

Thanks again.

Your explanation always right. There have a linksys router.
And someone have been configure it. A bundle of external mails
coming to my account, which send by yesterday.

However, I no sure how to do it...willing to learn it.
And I check from the linux machince with "nslookup" for user@acha.com

example:
nslookup acha.com

Non-authoritative answer:
Name: acha.com
Address: 202.71.138.147

It seem the domain name able to find.


rgds,
:newbie:

ok, so you need to know 2 things. the internal ip addresses of your gateway and your mail server. routers are normally 192.168.1.1, so that should be easy. open up a browser like firefox or IE explorer and put that in the url bar and hit enter. it should ask you for a user name and password, which you should enter. then you want to look for a tab called "forwarding". on my router i first have to click on "advanced" and then "forwarding". then i tell it to forward port 25 to 192.168.1.65, which is my mail server. save the changes and exit. you should be all set.

Hi,

Thanks you my friend :)

I manage to do it.

:cool: