How to setup an RedHat Email server with dns2go and sendmail?

[RoyWoo]

Can anyone help?
Can anyone tell me a useful website for this Linux Newbie?

[RoyWoo]

Sorry forgot to mention that I am using RedHat7.3, and I also heard rumor that my isp had blocked port25 and 80!!!
Can I still setup the server with ADSL?

Thank you very much!

[benoit Bruckert]

Question :
dns2go is like dyndns ??
If this is the case, the first thing to do is to check if port 25 is closed by your ISP. For this :
- you should have sendmail running on your redhat box as daemon.
- Connect to internet from any way but not your dsl connection, in order to have another address.
- then try telnet 25
if you have an answer, then the port 25 isn't blocked ! You can continue tand install the rest. IE configure sendmail and so on.... Not easy but funny !
If you have no answer, try just a ping to see if ip is OK if not, then may be you have another trouble ! If yes, then either sendmail has a trouble or, the port is blocked.
To check about sendmail,
try on your linux box
netstat -a | grep smtp,
if you have something like *.smtp LISTEN, then your sendmail is listening on 25 port .
Try then from your Linux box
telnet 127.0.0.1 25
You should have the same answer as the test from internet.

Configuration of sendmail isn't difficult, to accept email, but with your DSL config you will have to be careful with relay ! if you don't want spammer will use your bandwith !

Hope it may help
regards
Benoit

[RoyWoo]

Thank you Benoit,

I appreciate your advice very much and I just did what you mentioned.I also decided to use dyndns.org instead of dns2go.

Let me take some time to explain my situation in detail.

There are several ISPs available in my area. By using "nslookup -sil smtp.xxx.com", i found their SMTP servers fixed IP addresses, of course including my own ISP's mail server.
Then I typed "telnet xxx.xxx.xxx.xxx 25" to connect to each of these found SMTP servers. To a little disappointment, I found I could only connect to my own ISP's SMTP server which showed:
"Trying xxx.xxx.xxx.xxx...
Connected to xxx.xxx.xxx.xxx.
Escape character is '^]'.
220 xxx.xxx.com ESMTP"

However if I did the same thing to other ISP's SMTP server, it stopped after the line "Trying xxx.xxx.xxx.xxx..."

I also tred it with local address,
"telnet 127.0.0.1 25
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
220 localhost.localdomain ESMTP Sendmail..."
It seems it works only for the local network.

I am now quit convinced that my ISP had blocked port25!
I just installed RedHat7.3 and would like to host my own email server with sendmail + dyndns, how can I configure Sendmail to listen to other ports besides 25?
If I did that, can I send and receive email using xxx@roywoo.dyndns.org as usual?

Thank you for your kind attention once again!
Looking for your reply.

[benoit Bruckert]

hi,
It's easy to change the port to listen with sendmail,
in sendmail.cf,
place :
DaemonPortOptions=Port=,Addr=,Name=MTA.
stop /start sendmail, check with netstat -a with this new port,
try telnet localhost and see if smtp is answering..

Concerning dyndns, I don't think it's possible to do such a thing, I.e. that bind (DNS) is a standard, and email server are stored as MX, wich are always smtp !!
if you try nslookup with any options you have never the port where the mx is listening !!!
I cannot say that there are no solutions, but if there's one, i'm interested !

[benoit Bruckert]

oups,
I read again the details, and it seems for me that you didn't made the smtp test to your own server.
To make this test, first get your ip public address,
Second, connect to internet, with another line, and try telnet 25 it should answer the same thing as what you have when you telnet localhost 25 from the linuxbox....
Because all the tests you did concerned connection to other smtp servers as I understood.
Hope i'm enough clear for you..

regards
benoit

[RoyWoo]

Thx Benoit,

I am so surprise that you gave me such a prompt response!
I appreciate your help very much.

I tried what you mentioned again, this time with my notebook running WinXP on a 56K connection from another ISP. I found that I can telnet to all ISP's smtp server, but as I tried my own IP the telnet windows vanished and return to cmd.exe (under WindowsXP)

I think the ISP indeed blocked port 25! What can I do now, please adise...

Thank you very much.

[benoit Bruckert]

Answer after the W.E.
I'm terribly sorry Roy, but I think that there's no issue, if smtp (25) is blocked by your ISP which seems to be the case after all the tests, you cannot create your own mail server !!!
it's always possible to use another port, but it will work only for you, people who won't know the number of this port will not success to send email to you !!!
More practically, there's another way.
You can use fetchmail to download through pop3 email stored on internet mail boxes (but you cannot configure your own domain name !!), and still use sendmail to send messages.
The other way is to see with your ISP if they can open port 25 ! May be it's possible ??

regards
Benoit

[Noel B. Tigley]

Hi,

Check out the Mail Reflector service at www.no-ip.com.

[chilibowl]

i had the same problem after a fresh install of RedHat 7.3.
it seems that the default for sendmail in this version is to only listen on the 127.0.0.1 loopback. try editing /etc/mail/senmail.mc
comment out the line that says: DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')
see if that works. it think RedHat did this to avoid spam on your server.
hope this does it for you.

kerrin

[chilibowl]

oops. i fotgot to mention after you edit sendmail.mc type:

m4 /etc/mail/sendmail.mc > /etc/sendmail.cf

hit enter. this rebuilds the sendmail.cf file that sendmail refers to.
then restart sendmail.