I come from a culture that endorses lengthy greetings, but when emailing academic people, I personally prefer emails that are to the point. For example, if I'm emailing someone who doesn't know me (say Dr. Cooper), I'd rather write this:    Dr. Cooper,

    I saw your paper on foo bar and have some ideas on how to extend it to baz.    
    If you're interested and free this week, I'd like to discuss this with you over Zoom.

    Steve Jobs, Ph.D.
    Parallel Universe University
    

I'm also totally ok if someone writes to me like this:    (no hi and no name)
    
    I'm developing an algorithm which uses blockchain to store foo bar, similar to your recent paper on the baz technology.
    Can you share the code or tell me how you implemented it?

    Bill Gates,
    Product Manager, Apple Inc.

I wonder if academic people find it acceptable to just start an email and get to the point directly.  I know many technical people who do that.