My Email defaults are set up with a default sending address, but we want to use a different sending addresses in some places.
A global or exchange administrator account. Emails being hosted by exchange online.
For example, suppose that we normally have infusion sending emails as email@example.com but we’d like Quotes to be sent as firstname.lastname@example.org . Note: This will not work if the email addresses are not in the same tenancy.
Note this is copied direct from Microsoft documentation, located here: https://learn.microsoft.com/en-us/exchange/recipients-in-exchange-online/manage-permissions-for-recipients#use-the-eac-to-assign-permissions-to-individual-mailboxes
Use the Exchange admin centre (EAC) to assign permissions to individual mailboxes
In the EAC (https://admin.exchange.microsoft.com), click Recipients in the feature pane. Depending on the type of mailbox that you want to assign permissions for, click on one of the following tabs:
- Mailboxes: User or linked mailboxes.
- Resources: Room or equipment mailboxes.
- Shared: Shared mailboxes.
In the list of mailboxes, select the mailbox that you want to assign permissions for.
On the mailbox properties page that opens, click Mailbox delegation and configure one or more of the following permissions:
- Send As: Messages sent by a delegate appear to come from the mailbox.
- Send on Behalf: Messages sent by a delegate have " <Delegate> on behalf of <Mailbox>" in the From address. Note that this permission isn't available in the EAC for shared mailboxes.
- Full Access: The delegate can open the mailbox and do anything except send messages.
To assign permissions to delegates, click Add under the appropriate permission. A dialog box appears that lists the users or groups that can have the permission assigned to them. Select the user or group from the list, and then click Add. Repeat this process as many times as necessary. You can also search for users or groups in the search box by typing all or part of the name, and then clicking Search . When you're finished selecting delegates, click OK.
To remove a permission from a delegate, select the delegate in the list under the appropriate permission, and then click Remove .
When you're finished, click Save.