Hi HRD388797751ylr,
Thank you for reaching out.
It is not possible to change the message's sequence. However, if you wish, remove the main email message on the Send page so that only the Private message will appear on the recipient's side. You may also add the main message at the end of the main message. Check if this workaround works for you.
Refer to the information in the following help document: https://adobe.ly/3MgDosR.
Let us know how it goes.
Thanks,
Meenakshi
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