Exchange mail flow guides › Sender address in Outlook

How Outlook users can choose a different From address on Exchange on-premises: Send As, Send on Behalf, shared mailbox, add-in

On an on-premises Exchange Server, Outlook sends from the primary SMTP address of the user’s mailbox unless the user has the Send As or Send on Behalf permission on another mailbox or group. Exchange Server has no setting that lets a user send from one of their own secondary addresses; the setting that does this, SendFromAliasEnabled, exists only in Exchange Online. That gap is why Outlook add-ins such as ChangeSender exist.

Updated on 2026-09-21

What Exchange does without any extra configuration

A mailbox can carry many e-mail addresses, but only one of them is the primary SMTP address. The others receive mail. When the user writes a message, Outlook offers the mailbox itself as the sender, and the recipient sees the primary address.

Anything beyond that is a delegation. Microsoft documents the available permissions in Manage permissions for recipients (applies to Exchange 2016, 2019 and Subscription Edition): an administrator allows a user, the delegate, to send messages that appear to come from another mailbox or from a group. The important word is another. The permissions are granted on a separate recipient object, never on one of the user’s own additional addresses.

The four ways, side by side

Way	Who sets it up, and where	What the recipient sees	Where replies go
Send As	Administrator, on the other mailbox or group: EAC → Recipients → the mailbox → Mailbox delegation, or Add-ADPermission.	The other mailbox or group. Microsoft: “There’s no indication that the message was sent by the delegate.”	To the other mailbox or group.
Send on Behalf	Administrator, same place, or Set-Mailbox -GrantSendOnBehalfTo.	Both names: “<Delegate> on behalf of <MailboxOrGroup>”.	To the mailbox or group, not to the delegate.
A second or shared mailbox	Administrator creates the mailbox and assigns Full Access and Send As. Full Access alone opens the mailbox but does not allow sending from it.	The shared mailbox.	Into the shared mailbox, which every delegate has to watch.
An Outlook add-in that sets the sender	Administrator installs a server component on Exchange and the add-in on the PCs; the user picks the address in the mail form.	The chosen address, without “on behalf of”.	To the chosen address, which is delivered wherever that address lives: the user’s own mailbox for an alias, a distribution group for a shared address.

The first three are built into Exchange and cost nothing but administration. They fit when the other sender really is a separate entity: the mailbox of a manager, a team mailbox, a group. They fit badly when one person simply has several addresses — a second domain after a merger, a role address such as sales@ next to the personal one — because each address then needs its own mailbox or group, and replies go to that object first instead of straight into the user’s mailbox.

Granting Send As and Send on Behalf

In the Exchange admin center open Recipients, select the mailbox the user should send as, click Edit and go to Mailbox delegation. For a group the page is called Group delegation. In the Exchange Management Shell Microsoft’s example for Send As is:

Add-ADPermission -Identity "Helpdesk Support Team" -User Helpdesk -ExtendedRights "Send As"

Send on Behalf is a property of the mailbox or group itself and is set with the GrantSendOnBehalfTo parameter of Set-Mailbox, Set-DistributionGroup or Set-DynamicDistributionGroup. To check who may send as a mailbox or group, replace the name and run:

Get-ADPermission -Identity "Sales" | where {$_.ExtendedRights -like 'Send*'} | Format-Table -Auto User,Deny,ExtendedRights

Three details from the same Microsoft page save a support call. If a user holds both permissions on the same object, Send As is always used. A delegate cannot send from a mailbox that is hidden from address lists. And Send As can be granted on distribution groups, dynamic distribution groups and mail-enabled security groups as well, which is the built-in answer when several people should write as info@ and no one needs a mailbox for it.

Why a user cannot send from their own alias

Exchange Online has an organization setting for exactly this. Microsoft’s reference for Set-OrganizationConfig describes SendFromAliasEnabled as the parameter that “allows mailbox users to send messages using aliases (proxy addresses)” and marks it as available only in the cloud-based service. Exchange Server 2016, 2019 and Subscription Edition have no equivalent setting. On premises the choice is therefore between turning each extra address into its own recipient object with Send As, and an add-in that sets the sender address of the individual message.

One address for several people, several addresses for one person

Two situations come up again and again in support. The first: two or more mailboxes should send from the same address, for example sales@company.com. Exchange does not share one sender address between mailboxes. With ChangeSender the shared address is added to each user’s sender list, and for the incoming side you create a distribution group with that address and add the people who should receive the replies. The steps are in the knowledge base article How to use the same sender address for two Exchange mailboxes.

The second: one person answers for several addresses and wants everything in one inbox. Here the addresses stay ordinary secondary addresses of the mailbox, so nothing changes for incoming mail, and the add-in only changes what goes out.

What the add-in route looks like with ChangeSender

ChangeSender is an Outlook add-in with a server component for Exchange. It puts a send-as dropdown into the Outlook mail form, so the sender address is chosen per message. Around that choice it handles what otherwise goes wrong by hand:

• Replies match. When a user replies, the sender address is set to the address the original message was received on.
• Signatures follow. A signature named exactly like the sender address is switched in automatically when the address changes.
• Sent items can be separated into different Outlook folders depending on the sender address used.
• Keyboard shortcuts (CTRL-1, CTRL-2 and so on) select the most-used addresses.
• Different defaults can be set for new messages and for replies.

Both parts must be installed: the server component on the Exchange server and the add-in on every PC. The add-in alone looks as if it works, but the sender address does not change. ChangeSender supports Exchange 2000 through 2019 and Exchange Server SE with Outlook 2007 through the current Microsoft 365 Apps; a separate edition covers terminal servers and Citrix. The installation guide walks through both parts, and the download page has both installers.

Keeping the choice under control

Letting users pick a sender must not mean letting them pick any sender. The server installation of ChangeSender includes the utility “Configure ChangeSender Client Restrictions” with three settings per user:

Setting	What the user can choose
Default	The e-mail addresses configured for the user in Active Directory.
Single address	One specific address, with no choice.
Unrestricted	Any address, including shared addresses the user adds.

PCs in the Active Directory domain read these restrictions directly from Active Directory. For PCs outside the domain that reach Exchange over HTTPS, the utility exports a configuration file named after the user’s e-mail address, which is imported into the add-in on that PC. Details: How to restrict users’ choices for Send-As addresses in ChangeSender.

Which way for which case

• A colleague writes for a manager and that should be visible: Send on Behalf.
• A team writes as support@ and works from a common inbox: a shared mailbox with Full Access and Send As.
• Several people write as info@, replies should reach all of them in their own inboxes: a distribution group with Send As, or the add-in with the shared address.
• One person has several addresses or domains and wants one inbox, the right sender on every reply and the matching signature: the add-in.

Frequently asked questions

More in the Exchange mail flow guides, on the ChangeSender product page or in the knowledge base. Auf Deutsch: Absenderadresse in Outlook wählen mit Exchange on-premises.