Apple iOS Devices: 'Unable to Verify Information' for Office 365

​Yes, I know you are sure that the username and password you are using when configuring your iPad or iPhone are correct. And, yes the server address you are trying is also correct. Of course, its the one your IT guys gave it and you are not making a silly typo there. But still, you know as all other technology, apple devices can also drive you nuts when configuring exchange or office 365 email accounts on it.
Now when stated, you are putting all things correct, still the devices wont configure. Why?

Lets give you a hand in this situation. Apple devices, and sometimes Android devices also just wont configure with the ActiveSync or Exchange Server.

If you are in a situation like this, you can try the following:

1. Make sure the credentials are correct and active

Yes. If you have Outlook Web Access or OWA service available, just log into to make sure you are supplying the correct credential.
If you use Office 365, mail.office365.com it the URL. In other cases, you can try into mail.YourCompanyName.com, or contact your IT Helpdesk (or some colleague maybe, everybody should know that url).

2.  Remove your existing account

Remove all existing accounts and enter again your account details.
When you receive ‘Unable to verify’ pop up message, tap OK and add this account anyway by tapping save.
Tap Settings  > Mail, Contacts, Calendars > Exchange account > Account and turn off “Use SSL” and tap Done.

3. Turn the device Off or Restart it.

Yes. Sometimes, a pending restart to machine could be the reason for many types of error.  Do it if its taking this much pain in setting your mailbox. Restarting you device will give all connections and applications a fresh breathe of air.
Restart your device by pressing and holding the Sleep/Wake button until a red slider appears and slide the slider. Then turn your device on by pressing and holding the Sleep/Wake button until the Apple logo appears.

4. Reset your password. 

Don't keep it out of the 8-14 character window.  Passwords with too many characters can be the reason for failing verification.

5.  Switch to Cellular data.

In many cases, your work or open Wifi connection might be limited. It may be blocking access to the exchange server in many ways. So, if you are trying to connect over wifi, switch to 3G or 4G to make sure its not the internet connection playing you out.