Most schools carry a handful of addresses that only ever receive mail. Admissions@, exams@, office@, finance@.

For years we've worked around them with shared mailboxes and Send As permissions. Or we've just told staff to reply from their own address and hope nobody minds.

Microsoft announced on 7 October 2026 that send from alias is now generally available, after a preview that began in January 2022. Nearly five years. I'd honestly forgotten it was still in preview.

What actually changes

Previously an alias could only receive mail, and anything sent went out under the mailbox's primary address. With the setting turned on, Exchange Online keeps the alias as the sending address instead of swapping it back.

So the exams officer with exams@ as an alias can reply from it directly. Shared mailboxes still make sense when several people work the same inbox. This suits the one-person role.

Turning it on

It's one switch for the whole tenant, not per mailbox. You'll find it in the Exchange admin centre under Settings > Mail flow, or use Exchange Online PowerShell:

Get-OrganizationConfig | Format-List SendFromAliasEnabled
Set-OrganizationConfig -SendFromAliasEnabled $true

The change can take up to 60 minutes to apply. Users then pick the address from the From field in a supported Outlook client.

The bit trusts need to think about

Accepted domains holding mailbox aliases can now appear in the From line of outgoing mail, including domains that have never sent a message, unless sending from that domain is disabled.

In a trust, that could mean old school domains from before academy conversion. Or domains you registered purely so nobody else could.

Check SPF, DKIM and DMARC for each domain you intend to send from. DMARC needs an aligned SPF or DKIM pass. A defensive domain with DMARC set to p=reject can have its mail rejected if neither passes. Missing or incorrect authentication can also send legitimate mail into junk.

Before you flip the switch, list your accepted domains and check the authentication on each one. Then decide which aliases staff genuinely need.

And go in with realistic expectations. Microsoft still has some gaps to close before alias-sent mail supports everything the primary address does. Review the known issues in Microsoft's announcement before enabling it broadly.

How many receive-only addresses is your school or trust carrying right now?

Sources & further reading