CLOUD MESSAGE TRANSFER APPARATUS TO REDUCE NON-DELIVERY REPORTS

• US 20120158867A1
• Filed: 12/20/2010
• Published: 06/21/2012
• Est. Priority Date: 12/20/2010
• Status: Abandoned Application

• Current Assignee: Barracuda Networks Incorporated
• Original Assignee: Barracuda Networks Incorporated
• Inventors: LEVOW, ZACHARY
• Application Number:
  US12/973,727
• Publication Number:
  US 20120158867A1
• 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

Duplicate deliveries of email messages are prevented when a transient failure prevents delivery to some of a plurality of intended recipients but delivery to an other one or more of the intended recipients is successful. After receiving a list of recipients, an email body, and an “end of data” sequence, but prior to responding to the “end of data” sequence, an email server determines a transient failure reply code when any one of the address mailboxes of intended recipients is not available. A message-memorandum, such as the globally unique message-id and the address of one or more successful recipients is stored into a memorandum store. A subsequent transmission of the corresponding message will only be delivered to recipients who have not previously received it. Using this invention, the receiving/relay system would persistently track which recipients were allowed or refused by some unique characteristic of the message, such as internet message ID or a checksum of the distinct portions of the message/envelope that are unlikely to change (e.g. sender, recipients, body). Once a message has been identified as one that has been previously partially deferred, the recipients that were previously allowed would be ignored and delivery would be attempted only to the recipients that had not previously been allowed.

Claims

1. An apparatus comprising:

a circuit to receive electronic messages intended for a plurality of recipients and to respond to an end of data sequence with a type of SMTP status code when delivery status was mixed, coupled to

a circuit to determine a delivery status of mixed when delivery was successful to at least one of the intended recipients and was not successful to at least one other of the intended recipients.

2. The apparatus of claim 1 further comprising

a circuit to store recipients and characteristics of messages with a mixed delivery status into a message-memorandum store, coupled to the circuit to determine a delivery status;

the circuit to determine delivery status further coupled to a circuit to attempt transmission to intended recipients of a message not having previously received a substantially similar message;

coupled to

a circuit for determining if an intended recipient had previously received a substantially similar message by reading recipients and characteristics from the message-memorandum store.

3. The apparatus of claim 1 further comprising

a message-memorandum store comprising

a message characteristic store and

a message recipient store coupled to the circuits to read and store recipients and characteristics of a message which was successfully delivered to at least one of the intended recipients and was not successfully delivered to at least one other of the intended recipients.

4. An apparatus comprising:

a processor;

coupled to

a message-memorandum store;

a circuit to receive electronic messages intended for a plurality of intended recipients;

a circuit to determine if a message is substantially similar to a previously received message,

coupled to the circuit to receive electronic messages and

coupled to the message-memorandum store.

5. The apparatus of claim 4 wherein the message-memorandum store comprises:

a characteristic store for each message, and

a list store of recipients who have successfully received each message.

6. The apparatus of claim 4 wherein the circuit to receive electronic messages intended for a plurality of intended recipients comprises,

a circuit for transmitting a status code after receiving the end of data sequence.

7. The apparatus of claim 4 further comprising

a circuit to attempt transmission to an intended recipient not in the list store of a message substantially similar to a previously received message whose recipients are in the list store,

coupled to

a circuit to determine if an intended recipient is in the list store.

8. The apparatus of claim 4 further comprising

a circuit to determine a message delivery status of mixed status if a message delivery to a plurality of intended recipients has at least one success status with respect to the intended recipients and at least one temporary failure status with respect to the intended recipients,

coupled to the circuit to attempt transmission and

coupled to the circuit to the circuit for transmitting a status code.

9. The apparatus of claim 4 further comprising:

a circuit to store characteristics of each message which was intended to a plurality of recipients and was delivered successfully to at least one recipient and was not delivered successfully to at least one other recipient,

coupled to the characteristic store, and

coupled to the circuit to determine message delivery status of mixed status; and

a circuit to store into a list store the intended recipients of a message with mixed status to whom the delivery was successful,

coupled to the list store, and

coupled to the circuit to determine message delivery status.

10. A system to handle mail as a cloud service comprising a hardware server coupled by a network interface to a wide area network and further coupled to a plurality of local or remote mail transfer agents determine if an incoming electronic mail addressed to a plurality of intended recipients is substantially similar to a previous message which was successfully delivered to at least one of but fewer than all of the previously intended recipients, and attempt delivery without duplication, and respond to the email sender'"'"'s end of data sequence with a reply code of type failure when delivery is successful to at least one of but fewer than all of the intended recipients.

11. A computer-implemented method comprising

attempting to deliver an electronic message to a plurality of intended recipients prior to completing a DATA command dialog with a reply code;

responding to an end of mail data sequence with a reply code of transient failure on the condition that delivery to one or more of the intended recipients was a transient failure; and

storing into a memorandum store at least a message-memorandum for each intended recipient whose delivery was successful.

12. The computer-implemented method of claim 11 wherein attempting to deliver an electronic message to a plurality of intended recipients prior to completing a data command sequence with a reply code comprises the steps following:

performing recipient verification, and

passing each message to a Mail User Agent for each intended recipient before accepting the end of the mail data.

13. The method of claim 12 further comprising

depositing the message in a message store.

14. The method of claim 12 further comprising

determining when a condition of transient failure occurs before returning a 250 OK reply to the end of mail data sequence whereby the server is not configured to accept a message for future delivery.

15. The computer-implemented method of claim 11 wherein

responding to an end of mail data sequence with a reply code of transient failure on the condition that delivery to one or more of the intended recipients was a transient failure comprises

determining a message delivery status for each of the intended recipients after the receipt of an end of mail data sequence but prior to the transmission of a reply code to complete the DATA command dialog.

16. The method of claim 15 wherein the message delivery status for each of the intended recipients is selected from the following group:

success, transient failure, and permanent failure.

17. The method of claim 16 further comprising:

responding to the end of mail data sequence with a reply of transient failure followed by a text message comprising at least one of the following;

the recipients for whom the message status was success,

the recipients for whom the message status was transient failure, and

the recipients for whom the message status was permanent failure.

18. The computer-implemented method of claim 11 wherein

storing into a memorandum store at least a message-memorandum for each intended recipient whose delivery was successful comprises:

when the reply code to an end of mail data sequence is a transient failure reply code, determining to which of the intended recipients the message delivery was successful.

19. The method of claim 18 further comprising

determining a message-memorandum for each successfully delivered message comprising a hash of a message-id and the recipient address.

20. The method of claim 18 further comprising

storing into a computer-readable memorandum store a record of the successful delivery of a message to a recipient whereby a subsequent resending of the identical message to the recipient can be detected and duplicate delivery avoided.

21. A computer-implemented method for improved efficiency in handling electronic mail destined for recipients comprising

when an electronic mail session comprises a plurality of recipient commands:

determining a message-memorandum,

checking a memorandum store to determine the likelihood that the recipient has successfully received a substantially similar electronic mail,

disposing of the electronic mail,

determining a reply code, and

responding to an end of mail data indication.

22. The method of claim 21 wherein determining a reply code comprises

when delivery to at least one of the recipients is a transient failure,

selecting a Transient Negative Completion reply code.

23. The method of claim 22 for determining a reply code wherein a transient negative completion reply code comprises a 4 as the initial digit whereby a client apparatus may automatically determine to retry the transmission at a later time without human intervention.

24. The method of claim 21 wherein determining a message-memorandum for each of the recipients comprises

reading the message-id,

reading the recipient address, and

combining the message-id and the recipient address.

25. The method of claim 21 wherein determining a message-memorandum for each of the recipients comprises:

reading the message-id,

reading the recipient address, and

hashing the message-id and the recipient address.

26. The method of claim 21 wherein determining a message-memorandum for each of the recipients comprises,

hashing some or all of the mail data.

27. The method of claim 21 wherein determining a message-memorandum for each of the recipients comprises,

hashing an attachment to an electronic mail.

28. The method of claim 21 wherein determining a message-memorandum for each of the recipients comprises

computing a checksum of the message-id and the recipient address.

29. The method of claim 21 wherein determining a message-memorandum for each of the recipients comprises, computing a checksum of the data portion of the electronic mail session.

30. The method of claim 21 wherein

checking a memorandum store to determine the likelihood that the recipient has successfully received the electronic mail comprises:

querying a memorandum store with a message-memorandum, and at least one of

determining that a message-memorandum is not found in the memorandum store,

reading from the memorandum store a delivery status for a message-memorandum for at least one recipient.

31. The method of claim 21 wherein disposing of the electronic mail comprises

when the memorandum store indicates the condition that the recipient has likely successfully received the electronic mail,

dropping the electronic mail to that recipient;

when the memorandum store indicates the condition that the recipient has likely not successfully received the electronic mail,

delivering the electronic mail and

storing the message memorandum and the delivery status in the memorandum store wherein

delivery status is one of success and failure.

32. The method of claim 31 further comprising the step:

when the memorandum store indicates the condition that the recipient has likely permanently failed to receive the electronic mail,

dropping the electronic mail to that recipient;

33. The method of claim 21 wherein responding to an end of mail data indication comprises the steps following:

sending the reply code; and

a text string, the text string comprising at least one of the following

a list of intended recipients with successful delivery status,

a list of intended recipients with transient failure delivery status, and

a list of intended recipients with permanent failure delivery status.

34. The method of claim 33 wherein

the end of mail data indication is determined by a response to a DATA command.

35. The method of claim 33 wherein

the end of mail data indication is an end of data sequence.

36. The method of claim 33 wherein

the end of mail data indication comprises the five characters:

carriage return,

line feed,

period,

carriage return,

line feed, in that order.

37. An apparatus comprises

a network interface, coupled to

a mail transfer command receiver, coupled to

an “

end of data”

response generator, coupled to

a data store, and

a delivery agent communicatively coupled to a plurality of recipient mailboxes.

38. The apparatus of claim 37 wherein the data store contains message-memorandum, and their delivery status to each intended recipient.

39. The apparatus of claim 37 wherein the “

end of data”

response generator comprises

a circuit to generate a transient failure code when any one of the mailboxes intended recipients is either transiently or permanently not available.

40. A computer-implemented method for operating an email server comprising the steps following:

receiving at least a first recipient and a second recipient;

receiving DATA and an “

end of data”

sequence;

determining the email status for each recipient from among the following;

success,

persistent transient failure, and

permanent failure;

transmitting a persistent transient failure code in response to the “

end of data”

sequence when the email delivery status for the respective recipients are one of success and persistent transient failure;

transmitting a permanent failure code in response to the “

end of data”

sequence when the email delivery status for the respective recipients one of are success and permanent failure; and

transmitting a success code in response to the “

end of data”

sequence when the email status for the respective recipients uniformly successful.

41. The method of claim 40 further comprising

transmitting a persistent transient failure code in response to the “

end of data”

sequence when the email status for the respective recipients are one of persistent transient failure and permanent failure.

42. The method of claim 40 further comprising

transmitting a permanent failure code in response to the “

end of data”

sequence when the email status for the respective recipients are one of persistent transient failure and permanent failure.

43. A computer-implemented method for operating an electronic mail server comprising the steps following:

receiving a plurality of recipients in an SMTP mail session;

receiving DATA and an “

end of data”

sequence;

determining the email delivery status for each recipient from among the following;

success,

persistent transient failure, and

permanent failure;

transmitting a persistent transient failure reply code in response to the “

end of data”

sequence when the email status for the recipients comprise no permanent failures and at least one persistent transient failure; and

transmitting a success reply code in response to the “

end of data”

sequence when the email delivery status for the recipients are uniformly successful.

44. The method of claim 43 further comprising

transmitting a persistent transient failure code in response to the “

end of data”

sequence when the email status for the recipients are at least one persistent transient failure and at least one permanent failure.

45. The method of claim 43 further comprising

storing a globally unique email identifier and delivery status for each recipient for each email for which the server determines a persistent transient failure status at the “

end of DATA”

sequence.

46. The method of claim 45 further comprising

receiving a MAIL command, a message-memorandum, and at least one RCPT,

determining when the recipient does not have a success for the message-memorandum, and

transmitting the message to the recipient when the message has not yet been successfully transmitted to the recipient.

47. A software program product tangibly embodied on a non-transitory computer-readable storage device encoded with computer executable instructions:

to receive simple mail transfer protocol commands,

to check a database for delivery status of a message-id to each of a plurality of recipients,

to deliver the message to available recipients which have not yet received the message,

to update the database with the current status of message delivery, and

to respond to an “

end of data”

sequence with a status code derived from the combination of status of delivery to each recipient.