Does Observer Design Pattern suits for Email Box Monitoring based action

I am new in Design Pattern related concepts, I have to develop an app which will monitor an email box & if any new email/s comes, the app needs to execute few process and it will use the email data as an input for executions. This process can be sequential or parallel.

Eg. Email Box A receives an email E1. For this new Email E1 say, there are three operations needs to happen (down the line it can increase):

1. Find the Category & Sub-categories (which will run a parallel thread to find both) for Ticket T1
2. Create a ticket T1 in customer support app

I have one in mind but due to lack of comprehension which would be better approach I would like to seek your advice.

1. Publish-Subscribe Pattern

2. A simple logical programming:

   def execute():

    while True:
        email = emailbox.listen()
   
        if email.new_email > 0:
            content = email.content
            for e in email:
               category = Thread(target=find_category, args=(e,Q1))
               sub_category = Thread(target=find_sub_category, args=(e,Q2))
               category.start()
               category.join()
   
               sub_category.start()
               sub_category.join()
   
               cat = Q1.get()
               sub_cat = Q2.get()
   
               P1 = Create_email(e, cat, sub_cat)