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To test the message, select “Send all variations of conditional content” and the different versions will be emailed to the test addresses when you click “Send Test Messages”.
Sending a split test
At the Sending stage, you can determine the percentage that the message will tested on. Just type in a number in the “Split Test %” box.
Split Test % - Percentage of the audience who will receive the test emails. For example, if the campaign has two messages and you choose 10% of the audience, 5% of the audience will receive one email and another 5% will receive the other email. Then after a winner is selected, the remaining 90% of the audience will be sent the winning email. For a 50/50 split, the value should be 100%.
Sending to the winner
If you have set the winner to be sent automatically, this will happen as set by your email settings.
Split test winner - This is where you determine how the winner will be chosen for the split test. The winner will chosen option requires a winner be manually selected by a User. Automatically select a winner allows the User to choose the criteria that will determine the winner and the number of hours before a winner is selected. If the split test account setting is enabled, the automatic option will be the default selected and the settings will match the account settings (but can be changed).
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If you have set it to be manually sent, then you can go to the Reporting stage which is accessed via the list of broadcasts (the 
icon)
You will see an area like this:
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The reporting will show you how successful each version has been so .
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After reviewing the reporting, you can then choose the split test version, and click “Select Select winner and send” send and the remining remaining percentage of supporters not included in the test will receive the selected version.