Will they know if I select the preview option and see the msgs?
According to my research, unknown sender does not know that you have selected the preview option and see the message.
Here are the steps of my test:
Step 1: Received a message from an unknown sender and block.
Step 2: Unknow sender can only see that the message was sent successfully, they can still see you in the group chat and send you message but you can't receive them.
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