It's more effective to ask the (final) question in the first sentence. And if you want a clear answer, don't ask more than one question per email. People always read the first sentence but may not scan all the way down. After some practice you'll naturally start to write emails starting with the question but until then just write it normally, come to the summary at the end, and then cut and paste it to the start.
This is like a mini-abstract. Human nature is that you only scan the first few lines and if it's too long (and you're not my boss) then it'll get tossed aside.
People who want long emails are in the wrong business today.
People who like short emails have synchronization problems that can be resolved in a short breath. Otherwise if you have three questions, you’re talking about three back and forth replies. That synchronization sounds wasteful.
- In the same or a similar timezone as the person you're talking to
- The one initiating the conversation (this is often not an option if someone else emails you!)
- Don't need to keep a record of the conversation
- In a situation where a meeting or phone call makes sense
Note that many of these are often not the case in e.g. the FOSS community. I'm therefore not surprised that those on FOSS mailing lists avoid top posting.
You should not have three questions (it's lazy) . You should think about what the one question should be and ask that question. Then think about the answer and develop the next question.