In Exchange Online, you can give delegate access to your colleagues. This means you can grant access to any folder which is part of your mailbox to any colleague of yours. This takes collaboration between Team members to the next level. Delegate access enables users to access some or all the mailbox owner’s folders and act on behalf of the mailbox owner. The mailbox owner can be a user, or a resource, like a conference room. For example, a receptionist can be granted delegate permissions to a conference room’s calendar folder, to handle booking requests. Delegates can be granted access to the following folders: 

• Calendar
• Tasks
• Inbox
• Contacts
• Notes
• Journal

Let’s try and understand the types of delegations possible. There are 3 types of delegations as shown in the diagram below:  

1)    Delegate plus folder permission

When it comes to sending mail or scheduling meetings, delegates can be given “send on behalf of” permissions, so the recipient of an email or a meeting request that was sent by a delegate will see “delegate on behalf of mailbox owner” when they receive the email or meeting request in Outlook. Including the “send on behalf of” text is a client implementation detail – and can be created by using the “from” and “sender” values. The “from” value indicates the mailbox owner, and the “sender” value indicates the delegate that sent the mail.

2)    Folder permission

Users who are granted folder permissions and not delegate access are not able to “send as” or “send on behalf of” of a mailbox owner. They have access to the mailbox folders and might be able to create items in the folders, but they cannot send the items.

3)    Impersonation

If a service account impersonating a user sends an email or schedules a meeting for the mailbox owner, the message is “sent as” the mailbox owner. There is no way for the recipient to know the mail was sent by the service account. Typical example is if you have a Shared Mailbox called “sales@yourcompany.com” which is accessed by 5 people. So, when these people send mail from the shared mailbox, the Mail goes as sales@yourcompany.com .

Scenarios where delegation can work:

a)    Executive Assistant to the CEO updates the mails and Calendar for the CEO.

b)    Marketing Assistant in a Trade fair updates the Contacts so that the Sales                 Manager can view the New Contacts on his Phone immediately.

c)    Exchange allows you to share Task list with a colleague or even delegate it   to         your Assistant.  So, imagine you are on the road and your colleague updates            your task list with new details. The updated data gets synced with your mobile.

So, we can clearly see that if the feature of Delegated Access is used intelligently, it can greatly increase the productivity within an Organization.