I will try to make this problem clearer with some screenshots.
This can happen outside the sandbox.
I did not understand that the Amazon SAS console can set the SNS denial / complaint topic for the domain , as well as a separate SNS parameter for each confirmed email address ,

Thus, each verified email address can have its own SNS bounce / complaint topic if you want! If you want all of them to be the same, you have to go and install them on the console: tell each of them to use SNS, otherwise they have "Email Feedback Forwarding" set to "enabled", and this will override the setting at the domain level.

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