This is possible; however, you could set this up in Outlook (if its outlook) without needing POA.
However yes. Now here is the detail as we are a teaching community, not just a "do someones work" community.
You did a nice job of breaking down your steps, but the next step is to do some searches gainstg that, just that step even.
1. Block an Email from a specific email (isn't a step) but an outcome
So the step is,
Receive an Email, check to see if its from an email address you dont want
2. move the email to junk
3. Send an Email to the send that has a message
These are all easy steps that are document.
1. Use an Automated Trigger for when you receive an email (action)
1A/1B
Either
1A) add a trigger condition checking the sender to see if it matches the one(s) you want blocked
1B) no trigger condition, instead add a Condition that checks if the Email Address matches some list of email address to block
2. Use the Move Mail action to move it to the Junk Email Folder or whatever folder you want to configure
3. Use the Send Email Action
-Use the Triggers Sender Dynamic Property as the To
-Put whatever Subject you want (hey its a spam leave me alone)
-Put in any message you want
Done