Solved

SMTP port to remote Exchange Server is blocked

Posted on 2010-11-19
12
339 Views
Last Modified: 2012-05-10
We've been having issues receiving email from a specific Exchange server to our Exchange server.  Neither server has problems sending to any other server, so this appears isolated.  

One thing I noticed is that when running telnet mail.remotedomain.org 25, it does not show any banner.  When running netstat it shows SYN_Sent from our server to theirs, but never completes the handshake.  From another location, I can telnet ok to the mail.remotedomain.org server just fine.

What might be causing this problem?  I can only imagine it is being blocked by the firewall or the IP is being denied by Exchange.  I don't have access to the server unfortunately.  Anyone have any ideas on what might be causing this?
0
Comment
Question by:B1izzard
  • 4
  • 3
  • 2
  • +1
12 Comments
 
LVL 15

Expert Comment

by:getzjd
ID: 34175053
Are you sure the other server is actually an exchange server and not a spam appliance or filtering device?
0
 
LVL 31

Expert Comment

by:MegaNuk3
ID: 34175061
Have you pinged the server from both locations to see if the same IP address is returned?
0
 
LVL 76

Expert Comment

by:Alan Hardisty
ID: 34175070
Does it show No banner at all or something like:

220 ***************************************************************************
0
 
LVL 15

Expert Comment

by:getzjd
ID: 34175075
If it were blocked by the firewall specifically, then you should not even be making any type of initial connection.
0
 
LVL 31

Expert Comment

by:MegaNuk3
ID: 34175102
Pinger = pinged
Stupid iPhone autospell...
0
Do email signature updates give you a headache?

Do you feel like you are constantly making changes to email signatures? Are the images not formatting how you want them to? Want high-quality HTML signatures on all devices, including on mobiles and Macs? Then, let Exclaimer solve all your email signature problems today.

 
LVL 76

Expert Comment

by:Alan Hardisty
ID: 34175115
Consider it corrected : )
0
 

Author Comment

by:B1izzard
ID: 34175215
Here is the banner from a know good location:
220 remotedomain.org Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at  Fri
, 19 Nov 2010 10:14:51 -0800

When telnetting from the problem location to the remote server, it gives:
Connecting To mail.remotedomain.org...Could not open connection to the host, on port 25
: Connect failed

The same IP is returned in both locations, so DNS is not an issue.

I can't think of anything other than the firewall blocking, or Exchange blocking by ip.  Anyone think any differently?
0
 
LVL 76

Expert Comment

by:Alan Hardisty
ID: 34175228
It does sound like they are blocking you.

Can you test from another location or would you like one of us to test for you?
0
 
LVL 76

Accepted Solution

by:
Alan Hardisty earned 250 total points
ID: 34175349
This is what I see:

220 domain.org Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at  Fri
, 19 Nov 2010 10:39:55 -0800

That says to me that they are blocking you specifically.  Time to talk to their IT department.
0
 
LVL 15

Assisted Solution

by:getzjd
getzjd earned 250 total points
ID: 34175351
Yes, sounds like you are being manually blocked then.  This is the information we needed to see.
0
 

Author Closing Comment

by:B1izzard
ID: 34278182
Thanks.
0

Featured Post

Maximize Your Threat Intelligence Reporting

Reporting is one of the most important and least talked about aspects of a world-class threat intelligence program. Here’s how to do it right.

Join & Write a Comment

ADCs have gained traction within the last decade, largely due to increased demand for legacy load balancing appliances to handle more advanced application delivery requirements and improve application performance.
This process describes the steps required to Import and Export data from and to .pst files using Exchange 2010. We can use these steps to export data from a user to a .pst file, import data back to the same or a different user, or even import data t…
In this video we show how to create a User Mailbox in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Recipients >> Mailb…
In this video we show how to create a Distribution Group in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Recipients >>…

707 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

19 Experts available now in Live!

Get 1:1 Help Now