When an email is sent to the related contact, the Update Client Details app creates a task that is also added to the activity history of the account, as shown in the image below.
In Lightning -
In Classic -
Additionally, there are the managed fields of the Update Client Details app on the Account object, which get updated when an email is sent to the account, as shown below-
This helps you to keep track of when the account has received the form previously and by which e-mail. You can add these fields into your account layout for better understanding.
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