Welcome email after registration, yes/no? Why?

nope

Why not? I mean, you can't simply expect the user to explore every single core feature of your app. So, it's important to clearly communicate what you have to offer.

yes, because I want to know whether or not registration success or not ?

Absolutely a YES! A welcome email is a brilliant way to start showing the real value of your product to the user. You should be able to share content on how to best get started with your platform, any upcoming webinars and events, and the best ways to reach out for support. You could always use automations to get all of these emails up and running. If it doesn't come off as too much of a plug, you should check out what I'm building :D

A lot of companies practice this, I think it is necessary so that the user can see how the logs of where he registered.

Yes. It's kind of a confirmation of the registration.

Of course yes, it's a really good marketing strategy. And you need also other mails about the process.

Yes, since you want to welcome brand-new customers.

a welcome email after registration creates a friendly first impression, facilitates initial engagement, and acts as a great opportunity to convey essential information about your service, thus paving the way for a stronger customer relationship from the get-go!

Of course yes! I want to make sure there are no problems!