Google Gmail is used by millions of people as their primary mailbox. Application for Android and iOS is well prepared, but still a little far from the possibilities you have in the web version.
The truth is that it is not simple to migrate all the features of the web version to a screen much smaller than a computer. However, we can agree that Google is doing a good job.
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The new feature is proof of that. Google Gmail has long been crowding emails into "conversations." That is, when you are exchanging emails with someone else, emails are compiled into conversations. If you want to see the previous conversation you just need to click on the previously exchanged emails and you will be looking for what you need.
But not all users like it. It always depends on how you organize your email. Although I consider the conversations an advantage, I've found myself lost in the middle of that conversation looking for a particular attachment sent.
You can delete Google Gmail conversations in the Android and iOS app
In the web version you can eliminate these "conversations" and individualize emails. You'll have a thousand and one emails from the same contact, but you'll be able to easily identify a particular email conversation.