Send As permission, also known as SendAs permission, gives a user permission to use another recipient's e-mail address in the From address. For example, when you give the user Chris Send As permission on the mailbox of a user named Michelle, Chris can send e-mail messages that appear to be sent by Michelle, with no indication to the recipient that anyone other than Michelle sent the message. Or, if your organization uses a Help Desk distribution group, you can give Help Desk staff Send As permission on the Help Desk distribution group. That way, replies to messages sent to the Help Desk group appear to come from the group instead of an individual Help Desk technician.
To give a user Send As permission, you use Windows PowerShell
Before you begin
- To learn how to install and configure Windows PowerShell and connect to the service, see Use Windows PowerShell in Exchange Online.
- The Send As permission is different than the Send on Behalf permission. If the user Chris has Send on Behalf permission on Michelle's mailbox, when Chris sends an e-mail as Michelle, the From address shows Chris on behalf of Michelle. Microsoft Outlook users can configure Send on Behalf permissions on their own mailbox using delegates. Administrators can configure Send on Behalf permissions on any recipient type using the GrantSendOnBehalfTo parameter.
- Want more information about parameters? See An explanation of parameters.
Give a user Send As permission
Launch Windows PowerShell and perform the following steps:
001 | Import-Module msonline |
1) Import the module.
2) Create a credential-object stored in the variable $credimp
3) Create a new remote PowerShell connection against the PowerShell endpoint for Office 365
4) List the cmdlets available
A shortcut to the module is also available on the Start-menu (you can skip step 1 if launching this shortcut):
Run the following command:
Command:
Add-RecipientPermission <identity> -AccessRights SendAs -Trustee <user>
For example, to give the user named Joanna Vathis Send As permission for the Test mailbox , run the following command:
Example:
Add-RecipientPermission test@itprodev.onmicrosoft.com -AccessRights SendAs -Trustee joannav@itprodev.onmicrosoft.com
OR
Command:
Add-RecipientPermission "TEST" -AccessRights SendAs -Trustee "Joanna Vathis"
Joanna can now send messages that appear to come directly from the TEST mailbox.
Note By default, you are asked to confirm the addition of the Send As permission. To skip the confirmation prompt, use -Confirm:$false.
View Send As permissions
Use the Get-RecipientPermission cmdlet to display all the Send As permissions configured in your organization. You can filter the list to show Send As permissions granted to a specific user and to see the Send As permission on a specific recipient.
View Send As permission for a specific user
Run the following command:
Command:
Get-RecipientPermission - Trustee <user>
For example, to list the recipients for whom the user named Kim Akers has Send As permission, run the following command:
Command:
Get-RecipientPermission -Trustee joannav@itprodev.onmicrosoft.com
Joanna can send messages that appear to come directly from the recipients
View Send As permission on a specific recipient
Run the following command:
Command:
Get-RecipientPermission <identity>
For example, to list the users who have Send As permission on the TEST mailbox, run the following command:
Command:
Get-RecipientPermission "TEST"
The users listed can send messages that appear to come directly from the TEST mailbox.
View all Send As permissions you've configured in your organization
Run the following command:
Command:
Get-RecipientPermission | where {($_.Trustee -ne 'nt authority\self') -and ($_.Trustee -ne 'null sid')}
Note The filter hides the automatic Send As permission that allows a user to send messages from their own mailbox, and also any results from system objects like mailbox plans.
Revoke Send As permission
Run the following command:
Command:
Remove-RecipientPermission <identity> -AccessRights SendAs -Trustee <user>
For example, to revoke Joanna's Vathis Send As permission for the TEST mailbox, run the following command:
Command:
Remove-RecipientPermission "TEST" -AccessRights SendAs -Trustee joannav@itprodev.onmicrosoft.com 
Now Joanna can't send messages that appear to come directly from the TEST mailbox.
To skip the confirmation prompt, use -Confirm:$false.
How people use the Send As permission
Individual users or members of security groups with Send As permission can open their own mailboxes and send messages using the From address of the recipient.
Send As permission doesn't give a user access to another user's mailbox. To give an individual or members of a security group access to a mailbox, use the following command:
Command:
Add-MailboxPermission <mailbox> -User <user or security group> -AccessRights FullAccess
When you give someone access to a mailbox and Send As permission on the mailbox, that person can open the mailbox using their own credentials, compose new messages, and reply to messages in the mailbox.
An explanation of parameters
You use the Add-RecipientPermission, Remove-RecipientPermission, and Get-RecipientPermission cmdlets to add, remove and view Send As permissions. These cmdlets use the same basic parameters:
Identity This parameter specifies the target recipient. The user or group specified by the Trustee parameter can operate on this recipient.
You can specify any type of recipient. For example:
- Mailboxes
- Mail users
- External contacts
- Distribution groups
- Dynamic distribution groups
The Identity parameter is a positional parameter. The first argument on a cmdlet is assumed to be the Identity parameter when no parameter label is specified. This lets you specify the parameter's value without specifying the parameter's name.
Trustee This parameter specifies the user or group to whom you're granting the permission. This allows the user or group to operate on the recipient specified by the Identity parameter.
You can specify the following types of users or groups:
- Mailbox users
- Mail users with a user account
- Security groups
For the Identity and Trustee parameters, you can use any value that uniquely identifies the recipient.
For example:
- Alias
- Distinguished name (DN)
- GUID
- Name
- Display name
- LegacyExchangeDN
- E-mail address
Additional Information’s:
Give Users Send As Permission
http://help.outlook.com/en-us/140/ff852815.aspx