Exchange Disconnecting on EHLO with remote telnet

Posted by Timothy Baldridge on Server Fault See other posts from Server Fault or by Timothy Baldridge
Published on 2010-02-17T23:00:25Z Indexed on 2010/04/23 14:04 UTC
Read the original article Hit count: 483

Filed under:

exchange

|

exchange-2007

|

microsoft-smtp

|

c#

When I go to the local terminal on my Exchange box (SBS 2008) I can do this:

telnet 127.0.0.1 25
220 Exchange banner here
EHLO example.com
250 Server name

However when I go from another box, or from the actual IP of the server I get this:

telnet 192.168.21.20 25
220 Exchange banner here
EHLO example.com
421 4.4.1 Connection timed out

Connection to host lost.

The odd thing is, this server is currently in production and working fine (receiving mail for our entire domain). But my C# programs can't send mail to it (they get this same error).

Any ideas?

© Server Fault or respective owner

Related posts about exchange

Upgrade Exchange 2003 to Exchange 2010 – Part II

as seen on Simple Talk - Search for 'Simple Talk'
In Jaap's second article on upgrading straight from Exchange Server 2003 to 2010, he explains how to move the various services from Exchange Server 2003 to Exchange Server 2010 and fully decommission the Exchange Server 2003 servers. >>> More
Upgrade Exchange 2003 to Exchange 2010

as seen on Simple Talk - Search for 'Simple Talk'
In this article, the first of two in which Jaap describes how to move from Exchange Server 2003 straight to Exchange Server 2010, he shows what is required before moving mailboxes from Exchange Server 2003 to Exchange Server 2010. He shows how to upgrade Active Directory, install both Exchange Server… >>> More
exchange server 2010 Outlook Web Access - Exchange Control Panel WEB Interface

as seen on Server Fault - Search for 'Server Fault'
from what i can gather the mailbox bit of the web interface works fine.. when any of the users go to options (top right) and try to use some of the features such as the Organise Mail Delivery Reports to find messages etc... it comes up with a message .. "An item with the same key has already been… >>> More
Backup multiple Exchange Accounts without direct access to exchange server

as seen on Server Fault - Search for 'Server Fault'
For e-mail, we use Microsoft Exchange and it is hosted by 1and1.com. We have about 30 Exchange accounts that I would like to backup to a PST file. That is, for each account that we have (all 30), I would like to create a single PST file (1.pst thru 30.pst). I do not have direct access to the Exchange… >>> More
when using exchange 2010 it complains of not talking to Information Store service on exchange 2007

as seen on Server Fault - Search for 'Server Fault'
I am attempting to do an upgrade in my org from exchange 2007 to exchange 2010. I moved all the mailboxes and made sure my certificates were setup in exchange 2010. I then changed my ip forwarding rules to forward mail to my exchange 2010 box. I can receive email. I then powered off my exchange 2007… >>> More

Related posts about exchange-2007

when using exchange 2010 it complains of not talking to Information Store service on exchange 2007

as seen on Server Fault - Search for 'Server Fault'
I am attempting to do an upgrade in my org from exchange 2007 to exchange 2010. I moved all the mailboxes and made sure my certificates were setup in exchange 2010. I then changed my ip forwarding rules to forward mail to my exchange 2010 box. I can receive email. I then powered off my exchange 2007… >>> More
Disk I/O error copying a Exchange 2007 database

as seen on Server Fault - Search for 'Server Fault'
Hi all, A short time ago due to disk space I moved our Exchange database onto an external drive, the drive was new and the database was being backed up daily. I've now discovered the database is corrupt, I've run the Exchange utils to fix the database and this works but it corrupts again as soon… >>> More
Do I have to prepare Active Directory prior to installing an Exchange service pack?

as seen on Server Fault - Search for 'Server Fault'
I'm having trouble determining the proper procedure for installing Exchange 2007 sp3 on a Server 2008 R2 box running Exchange 2007 sp1. It is not clear on websites I have consulted (Microsoft TechNet and others) whether preparing Active Directory is only required on a NEW install of Exchange 2007… >>> More
Exchange 2007 Owa (OnlineVersion) can not authenticate

as seen on Server Fault - Search for 'Server Fault'
Exchange Authentication dll: https://red002.mail.emea.microsoftonline.com/owa/auth/owaauth.dll sending style is: request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; And sending following message destination=https://red002.mail.emea.microsoftonline.com/owa/testuser@xxxserver… >>> More
Issues with doing a P2V on Exchange 2007

as seen on Server Fault - Search for 'Server Fault'
I shutdown all Exchange services on the physical box and did a convert. Everything converted fine. Server booted up no issues and I could receive email from the outside world with no issues. But I am unable to send emails internally or externally. They just sit in the Outbox. I also disabled the… >>> More