Cannot receive mail

Tap "Mailboxes" to go back and then select "edit" There are several other options there you might double check. Including turning on/off the Unread only mailbox. You can then click "done" and then select which mailbox you want to view .. "all messages" will have all of them in it.

How to delete or move ALL emails at once in non-jail broken ipad or iphone
It took me weeks of research to figure out finally how to decode this yet another secretive secret of apple. There is a perfect way of deleting ALL emails at once without jailbreaking your iphone or ipad...and here it is:
>> Open Inbox >> Edit >> Mark All >> Mark As Read [Added May 21, 2014 by Adrian; this extra step makes the difference between success & failure for some.]
>> Open Inbox >> Edit >> Check/select the top message; it will highlight the move button.
>> Press and hold the move button and uncheck the message that you had checked earlier.
>> Lift all your fingers off from the ipad screen and leave it alone. Wait until all your messages pile up on the right hand portion of the screen (in ipad); iphone will give you the actual number of emails it has selected for the action. Now they are just waiting for your command to be moved ALL at once.
>> Choose trash to delete all of them or any other folder where u want to move them, like one piece. Remember this will replicate your action on the server so you will ACTUALLY move them or delete them on the server and not just the ipad.
Once you have moved all messages to the trash you can either leave them there for the scheduled cleaning or empty it right away by doing this: go to trash folder and touch Edit. The Delete All button shows up at the bottom of the screen. Hit it! You're done!
If you do not see the effects of your actions on the server make sure you have enabled your email accounts for such actions.
Tips:
1. Please give enough time (could take up to several minutes depending the number of emails to be moved) for the emails to be selected for the move. Your screen will become unresponsive while all emails are being packaged. Once emails are ready, in ipad, you will see them zoomed out on the right hand side of the screen, and in iphone you will see the message showing you the actual number of messages that have been selected.
2. Avoid purging very large number of emails, the mail app might freeze or crash. If your inbox has thousands of emails change your sync settings in mail settings to fill lesser number of emails in your inbox.
3. [Added Jul 20, 2014 by Adrian] Many people have reported needing to repeat the above procedure several times before it succeeds. (I too have found this to be necessary a few times on my iPhone but not on my iPad-go figure.) So my final tip is to repeat the procedure 3-4 times if the mail doesn't disappear the first time. In my experience, if your messages disappear momentarily and then reappear, repeating the procedure will eventually make them stay deleted for good.
4. [Added Sep 18, 2014 by Adrian] If you are using IOS 8, there is a setting that may reduce emails piling up on your device! Go to Settings -> Messages and select Keep Messages under the Message History header. You'll be able to choose to keep your messages for 30 Days, 1 Year, or Forever.

Settings/Mail, Contacts, Calendars then tap the account you're having trouble with.

Assuming you're using an IMAP account, tap the account user ID on the first line. Scroll to the bottom and tap Advanced.

Tap Deleted Mailbox. In the ON THE SERVER section, tap Trash (making the Trash mailbox on the server your "Trash" location). Back up to Advanced and make sure MOVE DISCARDED MESSAGES INTO: is set to Deleted Mailbox.

You may want to do the same thing for your Sent Mailbox (using Sent on the server for sent messages - so they're retrievable from your desktop).

This fix may result in all the old deleted messages on the iPad being moved to the server and then showing up again in your deleted messages on your desktop. The Mail app will eventually delete them as it does any deleted messages according to its settings.

Go to Settings>Mail, Contacts, Calendars. Under the Mail window - go to Show> and select the number of recent emails that you want the iPad to load in your email accounts.

While you are in the mail settings - tap on the email account, tap on the account in the next window, tap on Advanced in the next window and tap Delete - and select the amount of time that you want the emails to stay on the iPad.

In some mail accounts there will also be an option for Delete from Server - tap that and set it to never if you want to control when to delete your old emails.

Go back to your email inbox in the mail app and swipe down to the bottom of the window - there may be an option to "load more messages from the server" in blue letters. Tap that and you will download as many odl emails as you set up for in the Show recent messages setting. At the top of the inbox is a search field - type in keywords in that search field to find old emails.

You can also search for emails in the spotlight search. Go to the home screen and tap the home button and the search feature pops up. Type keywords in the search field at the top to find old emails there as well. When you tap on that email in the search, the mail app will open and you can read the email.

Your best bet is to contact Google tech support, this will save you a lot of frustration.

Hi,

You can check this link:
http://www.wikihow.com/Set-Yahoo!-Mail-Classic-As-Your-Default-Webmail

Thanks

Want to delete more than a single email message? You can easily delete multiple email messages from the iPad by using the Mail's edit feature. The button on the top right side of the inbox is the edit button. Touching this button will put your inbox into edit mode.
Once your inbox is in edit mode, you can select multiple messages by touching each message you want to delete. You then have the option to either delete them by pressing the delete button at the bottom of the screen or moving them to a specific folder by touching the move button.

Have you cleaned out you deleted box? Look in Yahoo mail settings for a setting delete after so many days.

Dear Sir,


If you want to delete all messages(spam) from your inbox just click on a box present left side of FROM button, it will select the all the messages now click on DELET button.It will delete all the messages from your inbox 1 page, then do it for all pages,it will delete the message pagewise.if you want delete spam messages there is option(EMPTY) nearer Spam button click on it it will delete whole spam mails.
For your reference to select all messages a pic is here