Delegate Others to Send Messages on Your Behalf
You can give other people permission to send email messages on your behalf. When messages are sent on your behalf, the From address shows your name and the name of the person who is sending the message. This is not the same a sharing your Inbox with another person. The person who is sending a message on your behalf is working in his own email account. When a new message is created, your name is selected from the From field drop-down menu as the From address.
You can also give permission to people to send messages as you. The From address shows your name and email address as the message sender, but the actual message is sent from the delegated person's Inbox.
In the screen capture below, Send As permissions reflect email@example.com and Send on Behalf of shows as firstname.lastname@example.org on behalf of email@example.com. In both instances, replies to the email sent will be delivered to firstname.lastname@example.org rather than email@example.com
Below are the steps to assign these permissions:
Go to the Preferences>Accounts page.
In the Primary Account Settings, The following users have delegated authority to this account section, click Add Delegate.
After selecting Add Delegate, the Delegate Permissions Wizard will appear. Here you will add the email address of the person you are delegating permission to within the Email: field. **This must be an internal user address.**
Check the permissions you want to give.
Once you have selected OK to add the address, it will now appear within the section titled The following users have delegated authority to this account along with the assigned permissions.
To preserve the changes, you will want to select Save in the upper-left of the Preferences tab.
Afterwards, an email message is sent to the person letting him know that he has been granted delegate permissions.