Solved

SMTP Communication

Posted on 2003-11-09
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Last Modified: 2013-12-14
Hi,
I installed several email servers but the SMTP cannot receive messages.

Let me explain how the  DSL network is working here (i don't know the name of the protocol):
Login on a "LAN" which we get the NIC's IP address is something like 10.140.x.x
then login to the ISP's network to get internet access which we get our public IP address.

I pointed the dns to forward all MXE (Mail Easy) to the public IP address.

PROBLEM: the problem is that SMTP is not receiving msgs from outside the "LAN". For instance, if I send an email from my ISP I receive the msg OK. If I sent a msg from hotmail/yahoo the msg never arrives. Note that POP3 is working fine.
I tried about 10-15 mailservers but the problem is still the same. Note also that web/FTP (port:80/21) is OK with dns.

Any solution?


Thanks!
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Question by:dasoviet
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6 Comments
 
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Expert Comment

by:vtobusman
ID: 9715921
ok do you have port 25 for you smtp forwarded on you dsl router ??
 if not forward port 25 from you external ip to you internal ip ....

on most dsl router this is done using the Virtual Server option??
 a little more info on you set up would also help..

do you have a static public ip address??
are you using a dsl router?
you know draw us a picture?
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Author Comment

by:dasoviet
ID: 9716491
hmmmm...
Port 25 is open.

Sounds interesting what you are saying.
Well,
From the dsl modem a cable is going to a switch. From the switch a "cable tv" is "eating" bandwidth and from another port of the switch the server / router is getting connection. As you mention above the problem could be between the server the switch and the modem.

switch is a simple 10/100 one not with routing capabilities.
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Accepted Solution

by:
vtobusman earned 63 total points
ID: 9716646
hmmm then i would invest in a dsl router one that can be configured...

here are some nice cheep ones

http://www.compgeeks.com/details.asp?invtid=DI-704-R   ( this is a Standard one )
and only 24 bucks
http://www.compgeeks.com/details.asp?invtid=DI-704P-R ( This has a built in print server )
  this one is like 35 bucks...

  Also you say port 80 Web and port 21 FTP is open... are you hosting web sites and or ftp services ??
  is so and port 25 is open and its on the same server as your web/ ftp server then is should work the problem may be some where else....
  some ISP's block port 25 on the network so that people cannot host their own mail servers... some people set them up so that the can send spam e-mails... makes good people like us suffer..

  try this internal on your network can you send smto messages ?? if so check you isp for blocking port 25 ask them to open it for you.. tell them you are in school or something and need it to finish a project you are working on... LOL
 
  also you can download a program called Sam Spade it will check your services for you located at
   http://samspade.org

  hope this helps you a little more...

 
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LVL 3

Assisted Solution

by:Felix2000
Felix2000 earned 62 total points
ID: 9758831
Many ISP filter you from sending or receiving anythings on Port 25 except being able to access their mail servers.  This is to prevent spammer and people running servers.  Not sure if this is the issue in your case.

You can test this by going to an ISP other than the one you have you mail server on and try to telnet to your mail server ip port 25 see if you can get through.



-=[ Felix2000 ]=-
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