Mail app not working with iCloud, new emails and recently sent not showing at all in the app.

Question

I've been using the iCloud mail for quite some time now

Answer 1

A lot of people have been unable to access Yahoo e-mail on their iPhones or iPads. My wife’s iPad was not downloading Yahoo mail, although her iPhone was. Both used IOS 8.2. We tried deleting the account several times and troubleshooting all of the other settings. The problem appears to have been that allowing the IOS to automatically create the account on the iPad resulted in the wrong settings for the incoming server. The following procedure, pieced together from two websites, fixed the problem for us. So far, so good.
https://portal.smartertools.com/kb/a2659/configure-imap-for-iphone-or-ipad.aspx
https://help.yahoo.com/kb/mobile-mail/imap-server-settings-sln4075.html
On the iPhone, tap Settings.
Tap Mail, Contacts, Calendars.
Tap your Yahoo account, then delete it.
Tap Add Account.
Tap Other.
Tap Add Mail Account.
Complete the Name, Address (email address), Password and Description fields.
Click Next.
Ensure IMAP is selected.
Enter the following incoming mail server information:
Incoming Mail (IMAP) Server - Requires SSL
Server: imap.mail.yahoo.com
Port: 993
Requires SSL: Yes
Hostname is mail.yahoo.com.
Username is your full email address
Password is the same password used to access webmail.
Enter the following outgoing mail server information:
Outgoing Mail (SMTP) Server - Requires SSL
Server: smtp.mail.yahoo.com
Port: 465 or 587
Requires SSL: Yes
Requires authentication: Yes
Username is your full email address
Password is the same password used to access webmail. It may have been entered for you.
Tap Next.
The iPhone will establish an SSL connection to your IMAP and SMTP servers.
That’s all!