How to send email from a shared mailbox
To send email from a shared mailbox, add the shared address to your own account as a send-as address in Gmail, or hold Send As permission on the mailbox in Microsoft 365, then set the From field to that address before you send.
The complaint that brings most people here is narrow: the shared mailbox receives fine, but every reply leaves from a personal address, so the customer answers one teammate instead of the team. Receiving mail and sending as the mailbox are two separate permissions, and only the first one gets set up by default.
On Gmail and Google Workspace, start at step 1. On Microsoft 365 (also written M365, and still widely called Office 365 or O365), skip to step 3, where the whole answer is Send As versus Send on Behalf. Step 6 is worth reading either way, because it is how you stop picking the right From address by hand on every reply.
Steps
- 1
Gmail: add the shared address under Send mail as
In Gmail, open Settings (the gear icon), then "See all settings," then the "Accounts and Import" tab (labeled just "Accounts" on some Google Workspace accounts). Under "Send mail as," choose "Add another email address," enter the shared address and the name customers should see, and Gmail sends a confirmation code to that address. Somebody with access to the shared mailbox has to enter or click it. Until it is confirmed, the address never appears in your From menu. Gmail also puts a "Treat as an alias" checkbox on the address, and leaving it checked is the usual choice when the shared address belongs to your own team, but do not rely on it to pick the From line for you: the reply-address behavior you want is the "When replying to a message" setting in the step below on setting a default.
- 2
Gmail: use delegation when the mailbox is a real account
If the support address is a full Google account rather than an alias, the other route is delegation. From that account, in Settings, "Accounts and Import," under "Grant access to your account," choose "Add another account" and enter the teammate. They then open the mailbox from their Google account switcher and reply from inside it. Google allows 10 delegates on a personal @gmail.com account and up to 1,000 on a work or school account, with about 40 able to access it at the same time in typical use, and it can take up to 24 hours before a new delegate can get in. Two caveats: a Workspace admin can turn delegation off for the whole domain from the Admin console under Apps, Google Workspace, Gmail, and Gmail records which delegate actually sent a message, so a curious recipient can see the individual address in the message details.
- 3
Microsoft 365: check which permission you actually have
Full Access (shown as "Read and manage") lets you open the mailbox and read it. It does not let you send from it. Sending is a separate grant, either "Send as" or "Send on behalf." An admin sets all three in the Microsoft 365 admin center under Teams & groups, Shared mailboxes: open the mailbox and set each one under Manage mailbox permissions, where they are listed separately as Read and manage, Send as, and Send on behalf. The Exchange admin center has Full Access and Send as under Recipients, Mailboxes, Edit, Mailbox permissions, Manage mailbox delegation, but it cannot set Send on behalf for a shared mailbox, so do that one in the Microsoft 365 admin center. If you are not an admin, this is the step to hand to whoever is.
- 4
Microsoft 365: pick Send As or Send on Behalf deliberately
The difference is what the customer sees. Send As is indistinguishable from the mailbox sending for itself: the message reads "Customer Support <[email protected]>" and replies come back to the shared mailbox. Send on Behalf shows "Your Name on behalf of Customer Support," which is honest but tells the customer they are dealing with one individual. Support teams almost always want Send As. Grant one, not both, but if somebody does end up with both, Microsoft documents that Send As is the one always used, so a personal name showing up on every reply means Send As was never granted or has not propagated yet.
- 5
Prove it with one test message
Send a message from the shared address to a personal address you can open, and read the From line the way a customer would. If it shows the shared address alone, you have Send As. If it shows a name on behalf of the mailbox, you have Send on Behalf. If the shared address is missing from the From menu entirely, the permission never landed, or it has not replicated yet: a permission change in Microsoft 365 can take up to 60 minutes to propagate and take effect, and Gmail send-as addresses do nothing until the confirmation code is used.
- 6
Set the default so you stop choosing
In Gmail, go back to Settings, "Accounts and Import," and select "make default" next to the shared address, then set "When replying to a message" to "Reply from the same address the message was sent to." That single radio button prevents most wrong-address replies. In Outlook, replying from inside the shared mailbox's own folders usually sets the From line for you, but a message you start from your own inbox will not, so keep the From field visible until you have seen how your version behaves.
- 7
Sending from a phone
In the Gmail app, tap the From row in the compose screen to switch to any send-as address you have already confirmed on the web; you cannot add a new one from the app. Delegated Workspace accounts show up in the Gmail app account switcher, though Google still describes that as rolling out, so check it on the phones your team actually uses. In Outlook for iOS and Android, a shared mailbox you have Full Access to can be added as its own account from the app settings, as long as both your own mailbox and the shared mailbox are in Exchange Online, and you then compose from inside it. Neither app lets you grant yourself a permission, so do the setup on a desktop first.
Frequently asked questions
Why does my reply come from my own address?
Because access to a mailbox and permission to send as it are two different grants. Being able to read a shared mailbox, whether through Gmail delegation or Microsoft 365 Full Access, never implies the right to send from it. In Gmail you fix it by adding the address under Settings, Accounts and Import, Send mail as, and confirming it. In Microsoft 365 an admin grants Send as on the mailbox. After that the address appears in the From menu, and you still have to select it unless you set it as the default.
What is the difference between Send As and Send on Behalf?
Send As makes the message look like it came from the mailbox itself, with no trace of the individual who wrote it. Send on Behalf shows the recipient a line reading "Your Name on behalf of Customer Support," and replies can be steered back to the individual. Send As is the usual choice for a support address, because customers should be replying to the team. If a person is granted both, Microsoft documents that the Send As permission is always used, so the reply goes out as the mailbox alone.