If you want to send a mail from another person's mail box, you need to be a delegate with permission (granted by the administrator) to Send as or Send on behalf of the owner of that mailbox. If you also want to open or view the content of the respective mailbox, you need to have Full Permission (again granted by the administrator).
- The Send As permission allows the delegate to send email from this mailbox.
- The Send on Behalf permission allows the delegate to send email on behalf of this mailbox. The "From" line in any message sent by a delegate indicates that the message was sent by the delegate on behalf of the mailbox owner.
If you are an Outlook client user, here is how you will send a mail as or on behalf of another person:
- In Mail, click Home > New Email. (Keyboard shortcut to create an email message - Ctrl+Shift+M).
- On the Options tab, in the Show Fields group, click From.
- In the From box, type the name of the person on whose behalf you are sending the message.
To select the name from a list in the Address Book, click From.
- Add recipients, a subject, and the contents of the message as you typically do.
If you are using OWA, then here is how you can do the same:
- Log in to your mailbox using Outlook Web App
- Click New mail above the folder list. A new message form will appear in the reading pane.
- Click the extended menu, and then click Show from.
- Select the email address that displays in the From field and delete it.
- Type the name of the user for which you have permission to send email. If you don't see the name in of the person you want to send From box, you can click Search contact & directory to search the directory of your organization.
- Add recipients, a subject, and the contents of the message as you typically do, and then click Send