Send As / Send on Behalf: Send from a delegated email address or shared mailbox in Outlook


This article will teach you some basic concepts about delegated email addresses or shared mailboxes, the "Send As" and "Send on Behalf" permissions, and how to invoke each permission.


What is a delegated email address?

An email address where you have been added as a delegate and granted Send As or Send on Behalf permissions. 

What is a Shared Mailbox?

An email account where multiple people have been granted access to its mailbox. Depending on the business need and how these are configured, they can be set up for one of three behaviors when those people respond to emails received in that mailbox.

What are those three response behaviors?

  1. Default: Responses to emails will appear with the name of whoever responded as the Sender of the email, i.e. "from: Kenny Li"
  2. Send As: Responses will appear as the shared mailbox itself, i.e. "from: ITS Shared Mailbox"
  3. Send on Behalf: Responses will appear with the name of the responder, appended with "on behalf of <the display name of the shared mailbox">, i.e. "from: Kenny Li, on behalf of ITS Shared Mailbox"

Where will these responses be stored after they are sent?

By default:

This can also be configured to save copies in the "Sent" folder of BOTH the SENDER and the SHARED mailboxes upon request. 

Can I have both Send As and Send on Behalf?

No. "Send As" naturally supersedes "Send on Behalf". You will need to decide which permission to set for it to work properly.

How do I request a new shared mailbox?

Please contact your local department IT for this request. If you do not know who they are, please email us at

How to use Send As / Send on Behalf permissions

Outlook on the Web / Outlook Desktop App on Windows (New Outlook)

  1. When composing a new email in Outlook on the web you will see that your UCSD Email Address is listed in the From section of the email message. You may need to enable the From field by clicking on Options at the top navigation bar and selecting "Show From".
    A screenshot of the "Send" section at top of emails

    A screenshot of the "Options" menu with "show from" option checked

  2. When you click on the From email, other email addresses will be listed that you can send from. You can also click on Other email address… to see other options you may have access to send from.
    A screenshot of the drop down menu in the "From" section at top of email

Outlook Desktop App on Windows (Classic Outlook)

  1. By default, the From field will not be displayed when you compose a message. To display the From field click on the Options tab. Click on the three dots at the far right and select From in the Show Fields section. Now the From field will be displayed when composing a message in the future.
    Options menu in the classic Outlook Desktop app

  2. When composing a message click on the From in the drop-down box and select Other E-Mail Address.
    "Send From Other E-mail Address" window

  3. Type in the email address here that you wish to Send As and click OK.
  4. The next time you compose a message the alternate email address will be available from the From drop down box.

Outlook App on Mac

  1. When composing an email, click on the From field, and other email addresses that you can send from will be listed. You can also click on Other email address… to see other options you may have access to send from.
    The "From" drop down menu for picking other email addresses

If you still have questions or need additional assistance, please contact the ITS Service Desk. You can call us at (858) 246-4357, email us at, or submit a ticket at