Replicating message queues between clustered email gateway systems

• US 20050228867A1
• Filed: 04/11/2005
• Published: 10/13/2005
• Est. Priority Date: 04/12/2004
• Status: Active Grant

• Current Assignee: Wellington Financial LP (Canadian Imperial Bank of Commerce), WatchGuard Technologies Incorporated (Gladiator Corporation)
• Original Assignee: Borderware Technologies Incorporated (Gladiator Corporation)
• Inventors: Osborne, Robert, Simpson, Bill, Gilchrist, Rod
• Granted Patent: US 7,584,256 B2
• Time in Patent Office: Days
• US Class Current: 709/206
• CPC Class Codes: H04L 51/23 Reliability checks, e.g. acknowledgments or fault reporting

Abstract

A method of “stateful failover” is provided that allows email gateway systems in a cluster to deliver email messages that have been accepted for delivery by a member of the cluster, but has failed with out delivering the messages. The method involves creating a backup copy of the messages that have been accepted for delivery by one email gateway system in the stateful failover cluster on one or more other email gateway systems in the stateful failover cluster. Upon detecting the failure of the email gateway system that accepted the message, another member of the stateful failover cluster that has access to the backup copy of the message queue takes responsibility for the delivery of the messages on the mirrored queue.

Claims

1. A method for processing an email by a plurality of email gateway servers coupled in a cluster, the method comprising:

receiving the email by a first email gateway server, the first email gateway server being configured to relay the email toward a destination;

copying the email to a second email gateway server, the second email gateway server being configured to relay the email toward the destination should the first email gateway server fail; and

relaying the email toward the destination by the first email gateway server or the second email gateway server.

2. The method of claim 1, wherein the relaying includes:

monitoring by the second email gateway server the relaying the email by the first email gateway server;

upon detecting the relaying the email by the first email gateway server was unsuccessful, relaying the email toward the destination by the second email gateway server; and

upon detecting the relaying the email by the first email gateway server was successful removing the email from the second email gateway server.

3. The method of claim 1, further comprising acknowledging receipt of the email after successfully completing the copying.

4. The method of claim 1, wherein the copying includes communicating the email via a secure dedicated network link between the first and second email gateway servers.

5. The method of claim 1, further comprising detecting by the second email gateway server failure of the first email gateway server, and synchronizing the first and second email gateway servers after the first email gateway server is restored to service.

6. The method of claim 1, further comprising processing the email in accordance with a policy before the relaying.

7. The method of claim 6, wherein the policy includes virus scanning, content filtering, security processing, hygiene filters, or combinations thereof.

8. The method of claim 6, wherein the processing the email is performed prior to copying the email to a second email gateway server.

9. The method of claim 8, further comprising transmitting status information corresponding to the processing the email to the second email gateway server.

10. A method for replicating email messages in a stateful failover cluster, the method comprising:

receiving by a source email gateway system an email message to be transmitted to a destination;

transmitting the email message from the source email gateway system to one or more sink email gateway systems in the stateful failover cluster;

acknowledging receipt of the email message by the source email gateway system;

forwarding the email message by the source email gateway system toward the destination;

if the source email gateway system successfully forwards the email message, notifying the one or more sink email gateway systems to recover storage resources associated with the email message; and

if the source server fails to successfully forward the email message, forwarding the message by the one or more sink email gateway systems.

11. The method of claim 10, wherein the source email gateway system or the sink email gateway system utilize simple mail transfer protocol (SMTP).

12. The method of claim 10, wherein the acknowledging is performed after the transmitting to the one or more sink email gateway systems is complete.

13. The method of claim 10, further comprising processing the email in accordance with a policy before the forwarding.

14. The method of claim 13, wherein the policy includes virus scanning, content filtering, security processing, hygiene filters, or combinations thereof.

15. The method of claim 13, wherein the processing the email is performed prior to copying the email to a second email gateway server.

16. The method of claim 15, further comprising transmitting status information corresponding to the processing the email to the second email gateway server.

17. The method of claim 10, further comprising managing the source email gateway system and the one or more sink email gateway systems as a cluster to share delivery configuration information.

18. The method of claim 10, wherein the transmitting is performed via a secure dedicated communications link between the source email gateway system and the one or more sink email gateway systems.

19. The method of claim 10, further comprising monitoring and analyzing the source email gateway system to detect if it has failed.

20. The method of claim 10, further comprising detecting a failure of the source email gateway system and synchronizing the one or more sink email gateway systems and the source email gateway system after the source email gateway system is restored to service to prevent duplicate message delivery.

21. The method of claim 10, further comprising automatically delivering messages by the one or more sink email gateway systems when a failure of the source email gateway system is detected.

22. The method of claim 10, further comprising delivering the email message by the sink email gateway system when manually commanded to do so upon a failure of the source email gateway system.

23. An email gateway cluster comprising:

a plurality of source email gateway servers, each of the source email gateway servers configured for receiving email messages and relaying the email messages toward a destination, each source email gateway server comprising a source message queue for storing the email messages from outside an email gateway cluster; and

one or more sink email gateway servers communicatively coupled to each of the source email gateway servers, each sink email gateway server comprising a backup message queue for storing email messages from at least one source email gateway server, the sink email gateway servers being configured for relaying email messages to the destination should the respective source email gateway server fail.

24. A source email gateway server comprising:

a first logical communications interface for receiving messages from a message source;

a source queue for storing email messages received via the first logical communications interface;

a second logical communications interface for transmitting messages to one or more destinations; and

a third logical communications interface for transmitting messages to at least one sink email gateway server, wherein the source email gateway server is configured to transmit via the third logical communications interface messages received via the first logical communications interface for backup.

25. The source email gateway server of claim 24, wherein the first, second, and third logical communications interface utilize a single physical communications interface.

26. A sink email gateway server comprising:

a first logical communications interface for receiving messages from a source email gateway server;

a backup queue for storing email messages received via the first logical communications interface from the source email gateway server; and

a second logical communications interface for transmitting messages to one or more destinations, wherein the sink email gateway server is configured to transmit messages stored in the backup queue via the second communications interface messages if the source email gateway server fails.

27. The sink email gateway server of claim 26, wherein the first and second logical communications interface utilize a single physical communications interface.