Queue : SMTP Relay to remote Active Directory Site

Recently I got a call from one of our client located in a remote Active Directory Site. Some users started complaining that they are not able to send and receive emails.

Upon investigation we found that the emails are not working for across site users. Local users and self email was working just fine.

Symptoms :

  • Emails are stuck in “SMTP Relay to remote Active Directory Site.”
  • Telnet Server FQDN 25 returns “220 ***********************************”
  • Sent emails are in “Sent Items Folder”.
  • Ping command returns with positive results.

Organization Details: Exchange Server 2010 with Multiple Active Directory Sites.

Note : The steps may work or may not work in different scenarios. Please consult a network specialists before making any changes.


Looking at the above symptoms it is very clear that there is a network problem. So without making any delay I contacted the Network Team Administrator from remote site. Found that they have introduced a new Cisco ASA 5500X series firewall.

Figure 1: Queue Viewer

Queue Viewer before making the changes in firewall.

To troubleshoot issues on Cisco Firewall please follow steps listed in this article and look for ESMTP Inspection.

Cisco ASA 5500

Both command line and GUI options are available to fix the issue in Cisco ASA Firewall.

Figure 2: Queue Viewer

Queue Viewer after making the changes in firewall.

Mailflow resumed.



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5 Responses to Queue : SMTP Relay to remote Active Directory Site

  1. Dinesh kadali says:

    nice lesson….Thanks for sharing your prod experiences!!

  2. Sarvesh says:

    Hey Sunder nice article
    I think disabling SMTP inspection on the Cisco ASA procedure is missing. Let me see if I can get that…

  3. Sunder says:

    Thank you for pointing that. Instead I have shared the Cisco article which directs for the same. If you have anything let me know I will add them.

  4. Nazeef says:

    Thanks Sunder for sharing your experience !

  5. Adil says:

    Great post, Always on point!
    your articles always work!