You have setup your account on your iphone or anroid phone and found that it authenticated successfully to your mail server but email is not pulling down and you recieve no error, or ‘can not get email’ or ‘the connection to the server failed’.

Try this, worked for me:

1) Locate the account within AD
2) Right click properties
3) Click the tab ‘Security’
4) Click the button ‘Advanced’
5) Click ‘Include inheritable permissions from this object’s server’
6) Click OK
7) Wait a few minutes
8) Try again