Next update, should have "select" button to help ease multiple delete message!!

As the title mentioned above, I hope you can add ‘select’ button to help ease the user to delete multiple message. It is because there are some users out there receive more than 25 mails per day. And I am MMORPG gamer, so just imagine how much email I got everyday. So, I hope you can add this feature in the next update! thank you… 

You could just highlight the day and press Delete.

In the message list, you can use shift-click and ctrl-click to select multiple messages, just like in almost every other Windows app.

just like John above me suggested, selecting multiple messages is already implemented in eM Client.
Hold SHIFT and use UP or DOWN arrows to select multiple messages that follow each other or hold CONTROL and CLICK the messages you wish to select and then either delete or move them wherever you need.
As my personal advice, if your inbox gets cluttered with emails from one address/game I suggest making a separate folder for this game content and setting up a rule that will move these messages from inbox to this new folder, so you can view them at your leisure, separated from your personal mail.

Best regards,