Message splitting

If you send an email to multiple recipients, and different rules are set to apply to these recipients, you would like each recipient to get the right version of your message. That is why CodeTwo Exchange Rules comes with the message splitting capability. This option is enabled by default. Use the links below to find out more about message splitting, and how to manage it.

How message splitting works

Message splitting, also called bifurcation, is a process during which the original message is split into several identical copies. The number of copies depends on the number of different emails that the program needs to produce by applying different rules. For example, if there are 6 recipients of a message and that requires the program to generate 4 different emails, the message is split into 4 copies. Each copy is processed separately by the program and each copy appears in the Sent Items folder (so you have multiple versions of the same email in Sent Items, each one with different rules applied).

If message splitting is disabled and a message is sent to several people, the program applies only the rule defined for the first person on the recipients’ list (and this rule is applied to all recipients).


A single message about the upcoming merger is sent to 6 people outside the organization: Anu, Drew, Mark, John, Pradeep and Giuseppe. Anu is the first recipient in the To field. There are 2 rules that apply to this message: one that adds a signature to outgoing mail, called Insert_signature, and the other (called Approve_merger) that forwards all email containing the word merger to the sender’s manager for approval.

The rules are executed in the following pattern:

Recipient Rules used
Anu Insert_signature
Drew Approve_merger
Mark Approve_merger
John Insert_signature
Pradeep Insert_signature and Approve_merger
Giuseppe none

When message splitting is enabled in CodeTwo Exchange Rules, the program divides all the recipients into 4 groups and sends out 4 copies:

  • the 1st copy, with the signature added, will be sent to Anu and John;
  • the 2nd copy, before being sent out to Drew and Mark, will be forwarded to the sender’s manager for approval;
  • the 3rd copy will be stamped with the signature and then forwarded to the sender’s manager. Once the email is approved, it will be sent out to Pradeep;
  • the 4th copy will be sent, without any modifications, to Giuseppe.

These 4 copies will also appear in the Sent Items folder of the sender if the SIU feature is configured correctly.

When message splitting is disabled in CodeTwo Exchange Rules, only the rule defined for Anu (the first person on the recipient’s list) is executed. This means that all 6 recipients will receive an email with a signature defined for Anu. Note that Drew, Mark and Pradeep will receive the email without it being approved by the sender’s manager.

There will only be 1 copy of this message in the Sent Items folder.

Important notes:

  • Exceptions to the first recipient rule: If you set up different signatures for users within and users outside your organization, emails sent outside your organization are never stamped with signatures designed for internal users. This holds true even if message splitting is disabled and the first recipient is an internal one. In other words, emails sent to internal recipients are stamped with the external signature as long as there is at least one external recipient in the To field, not necessarily listed as the first one.
  • Email envelope: No matter if you enable or disable message splitting in CodeTwo Exchange Rules, the envelope of an email is not changed: the To field of every email copy contains all the recipients. Only the body of each email copy is different, as a result of modification by different rules.
  • Submission queue: Split (bifurcated) messages are not inserted into the submission queue again. If the CodeTwo Exchange Rules Transport Agent is the last one on the list of your transport agents, and you have other agents that would process such split messages differently, you may want to reverse the agents’ priority to make the CodeTwo agent the first one to process your message queue. See this article for details.

How to enable/disable message splitting

By default, the message splitting capability is turned on. You can manage it from the Administration Panel:

  1. Click the Settings button on the toolbar.
  2. In the Program settings window, click the Message splitting tab. Here, you can turn the option on or off by selecting/clearing the Activate message splitting checkbox.

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