Add a custom button in the "MessageComposer" or "EmailComposer"
I need to add a custom button that, when clicked, will perform the same function as sending an email, but with an additional function that executes along with the sending. However, I'm unable to access the "MessageComposer" or "EmailComposer" component to implement it. Could you help me with this problem?
In the image below, this is how I want the button (outlined in red) to look when implemented.

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+1 on information on how to modify OOTB components - not sure if it's possible in Creatio, but it would really help a lot of scenarios where we end up having to do things in a suboptimal way because we don't have information on how to modify the OOTB components to do things like add buttons or take custom actions when a user interacts with the component.