Applies to all Outbound Email Security Gateways and Inbound Email Security Gateways using the Outbound / Relay feature.
If the Outbound Queue of your Email Security Gateway is collecting a large number of emails, there are a few things to check:
- View the outbound queue details under Performance Statistics section of the Basic > Status page of the Email Security Gateway's web interface. To the right of the In/Out Queue Size label, click on the second number to open a new window that will display some of the messages in the Outbound Queue. This will also display the delivery state (which may explain why they aren't being delivered).
- Use the telnet test on the Advanced > Troubleshooting page to telnet to the mail server(s) from the Barracuda, and make sure they are accepting connections on port 25. Just enter the hostname or IP address of the mail server you are trying to connect to, followed by a space, followed by 25 and click Begin Telnet. If the mail server is accepting connections on port 25 and returning SMTP 220 banners, you should see a 220 response.
- Perform this same telnet test from another workstation on port 25 (to the same mail server(s)) and verify they are accepting port 25. If they are not, this is why the mail in the Outbound Queue is not being delivered.
- Make sure your Email Security Gateway has an A DNS record and a PTR DNS record since some ISPs (like AOL and Yahoo) will require these DNS entries in order to receive email from your Email Security Gateway. For more information on PTR records, see Solution #00002295.
If the mail in your Outbound Queue is not reaching its destination and you would like to remove it, simply wait. Mail will remove itself from the Outbound Queue after 48 hours of retrying. It is possible to change the 48-hour expiration time by contacting Barracuda Networks Technical Support for assistance.
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