Email Signatures in New Outlook: Roaming Signatures Explained for Admins

By David, 2026-11-09, updated 2026-11-09

In new Outlook for Windows and Outlook on the web, email signatures are roaming signatures: they're stored in the user's Microsoft 365 mailbox rather than on the PC, so they follow the user to every device where that account is set up. Microsoft doesn't offer a Microsoft Graph API for managing them, so to set signatures centrally an admin has three supported routes: turn roaming signatures off and write each mailbox's signature with Exchange Online PowerShell, deploy an event-based Outlook add-in, or append a signature server-side with a mail flow rule.

The short version: Roaming signatures are on by default. While they're on, the signature parameters of Set-MailboxMessageConfiguration don't work. Set PostponeRoamingSignaturesUntilLater to $true if you want to write signatures into mailboxes centrally; use an add-in built on OnNewMessageCompose if you want to insert them while users write; use a mail flow rule if you only need a footer on every message.

What roaming signatures are

Classic Outlook for Windows used to keep signatures on each computer, so a new PC meant recreating them. Microsoft's roaming signatures feature moves them into the mailbox, where, in Microsoft's words, they "will be available on all devices where that account is configured." Users don't have to do anything to turn it on, and existing signatures aren't overwritten.

A few details matter for admins:

• Which accounts roam. Microsoft 365 and Outlook.com mailboxes. Exchange Server on-premises, third-party services and POP or IMAP accounts don't roam their signatures.
• What migrates. In classic Outlook, the signatures set as the default for new messages or for replies and forwards are copied to the mailbox. Any others stay local, under "Signatures on this device", where users can insert them but not edit them.
• What breaks. Microsoft says add-ins and tools that wrote signatures to disk or the registry "will no longer work when this feature is enabled." If you've been deploying signatures with a login script that drops files into the user profile, this is why they stopped appearing.

Which Outlook reads which signature

Signatures in new Outlook work much as users expect: they can create several, pick one while writing, and choose separate defaults for new messages and for replies and forwards, per account.

Moving users from classic Outlook to new Outlook

Signatures can come across. New Outlook's settings import includes signatures, but only if classic Outlook's "Store my Outlook settings in the cloud" option is on.

COM add-ins don't. Microsoft says COM add-ins aren't supported in new Outlook and organizations should move to web add-ins. If a signature tool relies on a COM add-in or on files in the user profile, plan its replacement before you move users.

The timeline. Microsoft has promised at least 12 months' notice before each enterprise stage, and says it will honor support timelines for classic Outlook until at least 2029. In February 2026 it moved the start of the enterprise opt-out phase to March 2027 (message center post MC949965). Microsoft hasn't published a date after which classic Outlook stops being available.

One more deadline for signature tools. Exchange Web Services in Exchange Online was disabled by default from 1 October 2026 unless an admin allowed it, and Microsoft says it will be "fully and permanently disabled" from 1 April 2027. If your signature tool, or your own script, still writes signatures over EWS, ask what it uses instead.

Three ways to manage signatures in new Outlook

1. Turn off roaming signatures and write the mailbox signature

This is the route Microsoft's own PowerShell documentation describes. PostponeRoamingSignaturesUntilLater is an Exchange Online setting that controls roaming signatures in Outlook on the web and new Outlook for Windows. Setting it to $true turns them off for both, and once they're off, Microsoft says admins "can use the signature-related parameters on the Set-MailboxMessageConfiguration cmdlet" to set signatures. Before that, turning roaming signatures off in Outlook on the web needed a support ticket.

Connect with an Exchange Administrator account, then:

# Check the current value (False means roaming signatures are on)
Get-OrganizationConfig | Select-Object PostponeRoamingSignaturesUntilLater

# Turn roaming signatures off for Outlook on the web and new Outlook
Set-OrganizationConfig -PostponeRoamingSignaturesUntilLater $true

# Write one user's signature and add it to new mail and replies
Set-MailboxMessageConfiguration -Identity "alex@contoso.com" `
  -SignatureHtml "<p>Alex Wilber<br>Sales Director, Contoso</p>" `
  -AutoAddSignature $true -AutoAddSignatureOnReply $true

What to know:

• The setting is tenant-wide. For classic Outlook for Windows, Microsoft notes the registry value still applies: set DisableRoamingSignatures to 1 under HKCU\Software\Microsoft\Office\16.0\Outlook\Setup, or the matching policy key.
• SignatureHtml accepts HTML, but any JavaScript is removed.
• Microsoft documents these settings for Outlook on the web, and some for new Outlook. The parameters with "Mobile" in their names apply to Outlook on the web for devices, not the Outlook mobile apps.
• The script above is the easy part. Filling each signature from the directory, assigning different templates to different groups, catching users who edit or delete theirs, and handling joiners and leavers is the part that turns a script into something you maintain.
• Classic Outlook and non-Outlook apps don't read this signature, so users on those clients need another route.

2. Deploy an event-based Outlook add-in

Microsoft's recommendation for software vendors is "the signature API based on event-based hooks", and it says it has "no plans to support roaming signature management in the Microsoft Graph API." An add-in that handles the OnNewMessageCompose event (requirement set 1.10) runs when a user starts a new message, reply or forward, and inserts the signature. It's supported in Outlook on the web, new and classic Outlook for Windows, the new Outlook for Mac, and Outlook for Android and iOS.

What to know:

• An admin has to deploy the add-in, or it has to come from a Marketplace listing.
• At most five event-based add-ins run at once, and on mobile only one runs, with a 60-second limit.
• It doesn't run when a user reopens a draft, and Microsoft lists a few compose surfaces where it can fail, such as replying to a meeting invitation with a note.
• Mobile support depends on the app version, and mobile needs the add-in-only (XML) manifest.

3. Add a signature server-side with a mail flow rule

An Exchange Online mail flow rule can append HTML or plain text to messages, with sender details from the directory such as %%DisplayName%% and %%Title%%. It works whatever client sent the message. Microsoft's own list of limits is the reason it's rarely used for the whole signature: it can't go directly under the latest reply, senders don't see it in Sent Items, images have to be linked rather than embedded, and you need an exception so it doesn't repeat down a thread. Our server-side vs client-side explainer compares this approach with the other two in detail.

Which route fits

• You want signatures that users see while writing, in Outlook on the web and new Outlook, with no add-in to deploy: route 1, mailbox signatures. Microsoft documents these settings for Outlook on the web and new Outlook, so test the Outlook mobile apps in your tenant, and plan an add-in or a mail flow rule for any client that doesn't pick the signature up.
• You still have classic Outlook or Mac users and want one approach for all of them: route 2, an add-in, accepting the deployment and runtime limits.
• You only need a legal footer on every message: route 3. Our guide to signature legal requirements by country covers what it has to say.
• You have a mix: combine route 1 for Outlook users with route 3 for the clients it can't reach, and scope the rule so nobody gets two signatures.

Where Atlas Ink fits

Atlas Ink, our signature product, automates route 1 and adds route 3 as an option. It deploys into your own Azure subscription, fills each signature from Entra ID read-only, and writes it into each mailbox through the Exchange admin API, so it appears in Outlook on the web, new Outlook for Windows and Mac, and Outlook for iOS and Android, on new mail and replies. A daily reconcile puts back any signature a user edits or clears, and templates are assigned by tenant, group or user. It never routes mail through Atlas.

It needs roaming signatures turned off, and it checks that for you: the Rollout tab shows whether the setting is in place, and our support guide on turning off Outlook roaming signatures for Atlas Ink walks through it. For classic Outlook and non-Outlook clients, you can turn on optional server-side stamping, which is one mail-flow rule in your own Exchange Online, scoped to the users you choose; it isn't available in GCC or GCC High.

Here's the Rollout tab's coverage panel in our demo environment. It's the real Atlas Ink console; the users are sample data:

For the governance side, see how Entra ID tokens fill a signature and how drift enforcement works.

FAQ

Where are signatures stored in new Outlook?

In the user's Microsoft 365 mailbox. New Outlook for Windows and Outlook on the web use roaming signatures, which are stored in the mailbox and available on every device where the account is set up, not in files on the PC.

Will my classic Outlook signatures move to new Outlook?

Usually. When roaming signatures roll out, classic Outlook copies the signatures set as defaults for new messages and for replies to the mailbox. New Outlook's settings import also brings signatures across, provided "Store my Outlook settings in the cloud" is on in classic Outlook.

Can admins manage roaming signatures with Microsoft Graph?

No. Microsoft says it has no plans to support roaming signature management in Microsoft Graph, and recommends that vendors use event-based add-ins instead. To set signatures centrally from the mailbox side, turn roaming signatures off and use Set-MailboxMessageConfiguration.

How do I turn off roaming signatures?

Run Set-OrganizationConfig -PostponeRoamingSignaturesUntilLater $true in Exchange Online PowerShell. That turns them off for Outlook on the web and new Outlook for Windows. For classic Outlook for Windows, set the DisableRoamingSignatures registry value to 1.

Why doesn't Set-MailboxMessageConfiguration change the signature?

Because roaming signatures are on. Microsoft's documentation says the signature parameters don't work while the feature is enabled in a cloud organization. Turn roaming signatures off first, then set the signature again.

Do signature add-ins work in new Outlook?

Web add-ins do. Microsoft supports event-based add-ins, including signature add-ins built on OnNewMessageCompose, in new Outlook for Windows. COM add-ins aren't supported in new Outlook.

Last updated 9 November 2026. Microsoft details are drawn from Microsoft Support and Microsoft Learn as of November 2026: Outlook roaming signatures, Set-OrganizationConfig, Set-MailboxMessageConfiguration, Create and add an email signature in Outlook, Import settings to new Outlook for Windows, Control the installation of new Outlook, New Outlook for Windows: a guide to product availability, event-based activation and on mobile, signatures and disclaimers in Microsoft 365, and the Exchange team's EWS retirement update. Microsoft changes Outlook often, so check the current documentation before you plan around a date.