Boomerang uses Simple Mail Transfer Protocol (SMTP) to transmit email messages over the Internet.  The clustered and fault tolerant Boomerang VmWare cloud provides geographical redundancy for all inbound SMTP traffic between two split locations.   Inbound SMTP traffic is routed into the Boomerang platform via a set of clustered DNS services which in turn route SMTP traffic toward the code Boomerang service layer.

The Boomerang service in turn performs SMTP routing (both inbound & outbound) at its core cloud layer, thus ensuring full fault tolerance. In the unlikely event of a network / routing issue upstream, traffic is dynamically re-routed to our alternative location thus ensuring 100% service availability for both DNS & SMTP services.


Email delivery statuses

A default status (Sent) is applied to all email messages processed by Boomerang.  A status update is returned by the recipient's email gateway and Boomerang automatically updates the message transaction with this new status.  A summary of the delivery statuses for SMS is provided in the table below.


Status (Message level)AbbreviationDescription
Opened(O)The message has been opened by the recipient which is denoted by the fact the images contained in the email have been downloaded by the recipient.
Delivered(D)The recipient's email gateway provider has returned a delivered status denoting that the message has been accepted by the gateway and pushed to the recipient's inbox (although the message could still be filtered by local spam filtering rules).



Failed(F)The end user’s email gateway provider has returned a Failed status denoting that the email address is invalid or cannot be reached.
Undeliverable(U)The message could not be sent by the Boomerang gateway as a problem was identified with the end email address.
Expired(E)The message was not terminated at the end user’s device within the retry period (48 hours).
Sent(S)The message was submitted by the Boomerang gateway but no status update has been received from the recipient's email gateway