Exchange Web Services (EWS) Managed API

 EWS Managed API is used to create client applications that target Exchange Web Services (EWS). It provides various methods to create and alter the office 365 exchange online settings and mail Exchange mailbox. For further details follow the references provided below

1. http://msdn.microsoft.com/en-us/library/exchange/jj220499(v=exchg.80).aspx

2. http://msdn.microsoft.com/en-us/library/exchange/gg591267(v=exchg.140).aspx

Code Samples:

1. http://code.msdn.microsoft.com/Exchange-2013-101-Code-3c38582c#content

2. http://msdn.microsoft.com/en-us/library/exchange/dd633696(v=exchg.80).aspx

Sign up for an Office 365 Developer Site

1. You may already have access to an Office 365 Developer Site. If not then click on Create Account

2. You’ll have to wait for your Developer Site to finish provisioning. After provisioning is complete, refresh the admin center page in your browser. Then, click the Build Apps link in the upper left corner of the page to open your Developer Site. 

3. Now click on 'Build an App' tile. On the right side you will be asked to add the Napa Office 365 Developement tools. Click AddIt as shown in the figure below.

4. That's it. Now after you have a development environment and an Office 365 Developer Site, you can start creating apps for Office and SharePoint. Have fun

Reference: http://msdn.microsoft.com/en-us/library/fp179924.aspx

Use Windows PowerShell for Exchange Online

A. Install Power Shell 3.0

1. Install the full installation of Microsoft .NET Framework 4.0 (dotNetFx40_Full_setup.exe) from the Microsoft Download Center at http://go.microsoft.com/fwlink/?LinkID=212547.

  Or, install Microsoft .NET Framework 4.5 (dotNetFx45_Full_setup.exe) from the Microsoft Download Center at http://go.microsoft.com/fwlink/?LinkID=242919.

2. Install Windows Management Framework 3.0 from the Microsoft Download Center at http://go.microsoft.com/fwlink/?LinkID=240290.

B. Install Windows Azure Active Directory Module ( Microsoft Online Services Module)

Install Microsoft Online Services Module to connect to your local PowerShell session and create your Microsoft Online Office365 Administration session.

- (32-bit version) http://go.microsoft.com/fwlink/p/?linkid=236298

- (64-bit version) http://go.microsoft.com/fwlink/p/?linkid=236297

C. Configuring Power Shell

Now Open a PowerShell session and import the MS Online Module using command;

Import-Module MsOnline

Windows PowerShell script execution must be enabled on the computer you use to connect to Exchange Online. To enable script execution for signed scripts, run the following command in an elevated Windows PowerShell window.

 Set-ExecutionPolicy RemoteSigned

Connect to Exchange Online using Powershell

1. Open Windows PowerShell.

2. Run the following command.

$UserCredential = Get-Credential

3. In the Windows PowerShell Credential Request dialog box, type the user name and password of an account in your Exchange Online organization, and then click OK.

Run the following command.

4. Run the following command.

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/ -Credential $UserCredential -Authentication Basic -   AllowRedirection

5. Run the following command.

Import-PSSession $Session

Reference: http://technet.microsoft.com/en-us/library/jj984289(v=exchg.150).aspx