Depending on your email habits you might also have a problem with maintaining such a big inbox. However, it would be near impossible to clean up an inbox with 50,000 unread entries.
Now the drastic approach here is move everything away from sight, into Archive view. This way, nothing is deleted, and You can still search for your messages by keyword.
Here’s a simple way to doing this.
First, select all the messages currently on-screen by clicking the “All” selection option either above or below the message list.
Gmail will now tick the checkbox on all the messages currently on screen. However, you might still have thousands not covered by the current view. Gmail will ask you if you want to select all the conversations, including those out of view.
Click the link, and Gmail will now select everything, including message threads outside of the current screen.
Next step would be to click the “Archive” button to send all the selected conversations outside of “Inbox view.”
You can repeat the sequence regularly for maintenance, or whenever you get overwhelmed by thousands of messages in your inbox.
Gud lak! 😀