Steps for Cleaning and maintaining Yahoo Mailbox:
1. Routine cleanup of mailbox by making sure that you check your mailbox at least once in a day and delete or move the emails that are read by you in order to keep the inbox empty if possible at the end of the day.
2. You can configure your mailbox by using Yahoo mailbox assists to manage your messages.

Click options in the Yahoo Mail.

Select Import contacts.

Type in your earlier email address and password.

Now type in your new email address and password.

*Messages and contacts will be transfer by default now.

* Check the boxes for “send a message to my contacts.” and “I have read the terms of use.”

* Click “Confirm”.

You can also use Yahoo filtering features under yahoo mail to arrange a separate folder where emails from different senders will get delivered directly. You can name the folder according to your requirement. Yahoo will shift your less-important emails to folders called Promotions or Social.

To use filters to organize Yahoo mail follow the directions:

Click the Settings icon and select More Settings.

Select Filters.

Add new filters by entering the name. you can also set rules for your folder.

3. Do not provide your email on every website that you visit doing so will subscribe you to their automatic email system, so you would like to avid it if you already have a lot of emails rushing in already.

4. You can also try using an email cleaning tool. There are many tools available for keeping your mailbox clean, you can try some out to check which one works best for you.