This document describes how to troubleshoot delivery issues on the Email Security Appliance (ESA).
How to troubleshoot delivery issues on the ESA?
Cisco recommends that you have knowledge of these topics:
Track an outbound message through the mail logs or Message Tracking
Access to the CLI of the ESA
The information in this document is based on AsyncOS for Email Security.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
The ESA is able to receive mail but messages do not appear to be arriving at their destination. How do I determine why the ESA is not sending mail to a specific domain or domains? There are a variety of reasons an ESA may be unable to send messages. This article will focus on debugging issues with a remote domain.
Run the tophosts command and sort by Active Recipients in order to see which hosts have the largest delivery queue.
mail.example.com > tophosts
Sort results by:
1. Active Recipients 2. Connections Out 3. Delivered Recipients 4. Hard Bounced Recipients 5. Soft Bounced Events >
Run the hoststatus command in order to check the used MX records and the status. If "Host up/down:" is unkown or down, try sending a message to that host using SMTPPING tool as shown below and see if the status changes. Host status will show the status of the last attempted delivery.
mail.example.com> hoststatus cisco.com
Host mail status for: 'cisco.com' Status as of: Wed Sep 17 11:49:42 2014 CEST Host up/down: unknown
Counters: Queue Soft Bounced Events 0 Completion Completed Recipients 0 Hard Bounced Recipients 0 DNS Hard Bounces 0 5XX Hard Bounces 0 Filter Hard Bounces 0 Expired Hard Bounces 0 Other Hard Bounces 0 Delivered Recipients 0 Deleted Recipients 0
Gauges: Queue Active Recipients 0 Unattempted Recipients 0 Attempted Recipients 0 Connections Current Outbound Connections 0 Pending Outbound Connections 0
Oldest Message No Messages Last Activity Wed Sep 17 11:49:39 2014 CEST Ordered IP addresses: (expiring at Tue Mar 04 08:16:06 2014 CET) Preference IPs 10 126.96.36.199:25
Run the nslookup command in order to verify if MX records for recipient domain is valid.
Please enter the host or IP address to resolve. > cisco.com
Choose the query type: 1. A the host's IP address 2. AAAA the host's IPv6 address 3. CNAME the canonical name for an alias 4. MX the mail exchanger 5. NS the name server for the named zone 6. PTR the hostname if the query is an Internet address,
otherwise the pointer to other information 7. SOA the domain's "start-of-authority" information 8. TXT the text information > 4
Run the dnsflush command, if the DNS record has been corrected in order to pick up new MX record.
Are you sure you want to clear out the DNS cache? [N]> Y
Run the SMTPPING tool for connectivty test and send a test message.
Choose the operation you want to perform: - RAID - Disk Verify Utility. - DISK_USAGE - Check Disk Usage. - NETWORK - Network Utilities. - REPORTING - Reporting Utilities. - TRACKING - Tracking Utilities. - RELOAD - Reset configuration to the initial manufacturer values. > network
Choose the operation you want to perform: - FLUSH - Flush all network related caches. - ARPSHOW - Show system ARP cache. - NDPSHOW - Show system NDP cache. - SMTPPING - Test a remote SMTP server. - TCPDUMP - Dump ethernet packets. > smtpping
Enter the hostname or IP address of the SMTP server: [mail.example.com]> cisco.com
The domain you entered has MX records. Would you like to select an MX host to test instead? [Y]>
Select an MX host to test. 1. aer-mx-01.cisco.com 2. alln-mx-01.cisco.com 3. rcdn-mx-01.cisco.com > 2
Select a network interface to use for the test. 1. Management 2. auto >
Do you want to type in a test message to send? If not, the connection will be tested but no email will be sent. [N]> Y
Enter the From e-mail address: [email@example.com]>
Enter the To e-mail address: [firstname.lastname@example.org]> email@example.com
Enter the Subject: [Test Message]>
Enter the Body of the message one line at a time. End with a "." on a line by itself. Test only .
Starting SMTP test of host alln-mx-01.cisco.com. Resolved 'alln-mx-01.cisco.com' to 188.8.131.52. Connection to 184.108.40.206 succeeded. Command EHLO succeeded Command MAIL FROM succeeded. Command RCPT TO succeeded. Command DATA succeeded. Mesage body accepted. Test complete. Total time elapsed 1.48 seconds
Choose the operation you want to perform: - FLUSH - Flush all network related caches. - ARPSHOW - Show system ARP cache. - NDPSHOW - Show system NDP cache. - SMTPPING - Test a remote SMTP server. - TCPDUMP - Dump ethernet packets
Run the delivernow command and force the ESA to re-attempt delivery to all hosts or a specific host.
Please choose an option for scheduling immediate delivery. 1. By recipient domain 2. All messages > 2