Office 365 email signature management for every Microsoft 365 mailbox
Microsoft gives a tenant two ways to put a signature on outbound mail, and neither of them was built to manage a company's brand. This page explains both, says where AutoSignature sits, and what it takes to connect a tenant.
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The two Microsoft methods
Organization-wide disclaimers in Exchange Online
A mail flow rule appends a block of HTML to messages as they leave the organisation. It is reliable for a legal disclaimer and it covers every client, including phones, because it happens on the server.
- The sender never sees it. What is in Sent Items is the message without the block.
- It appends to the bottom of the thread, so a long reply chain collects a stack of disclaimers.
- It cannot use per-person data beyond a handful of Active Directory attributes, and formatting options are thin.
- It is skipped on encrypted mail, which in a regulated business is exactly the mail that needs the disclaimer.
Client-side signatures in Outlook
The signature is set on the mailbox or in the client, so the sender sees it while writing and it sits above the quoted text where a reader expects it. Roaming signatures keep it with the mailbox rather than on one computer.
- It is the signature people mean when they say signature: name, title, phone, logo, in the right place.
- Without management, each person sets their own, which is the problem you came here to solve.
Managed client-side signatures, with your mail flow rules left alone
AutoSignature sets the signature on the mailbox from a central template, filled per person from Entra ID directory fields. The sender sees it in the compose window and in Sent Items, it renders in Outlook on Windows and Mac, the new Outlook and Outlook on the web, and the short variant covers phones.
- Your existing mail flow rules stay as they are. Many companies keep one for the legal disclaimer and let AutoSignature own the visible signature.
- Mail is not routed through us, so nothing changes about delivery, encryption or your compliance boundary.
- Directory fields fill per person: name, job title, department, phone, mobile, office, photo and pronouns.
- Groups follow the attributes your tenant already has, so a department is a group without new lists to maintain.
Connecting the tenant
What the permission grant covers
A global administrator approves the connection once, on the standard Microsoft consent screen. The permissions are scoped to what the product does: read directory profiles, and set signatures on the mailboxes in scope.
- No permanent admin session, no service account with a password to rotate.
- The grant is listed under enterprise applications in your own tenant and you revoke it there.
- Message bodies are not read and not stored.
- Hybrid tenants with mailboxes still on premises are covered through the Exchange signature management path.
After the connection
The directory appears in the console, you map the fields, you build the set, you deploy to one group and check it, then you widen. The whole sequence is on the how it works page, and it is an afternoon.
What the buyer usually asks
How do you centrally manage email signatures in Office 365?
Microsoft gives you one built-in route for centralized email signature management: an organization-wide disclaimer applied by an Exchange Online transport rule. It appends the same block to outgoing mail for a whole group, but it cannot fill in each person's name, title or phone from Entra ID, and nobody sees it while they write. For per-person Office 365 signature management you connect a tool that writes the signature into each mailbox, which is what AutoSignature does after a single admin consent.
Can I manage Outlook signatures centrally for all users?
Yes. AutoSignature sets the signature on the mailbox itself, so it becomes the default for Outlook on Windows and Mac, the new Outlook, Outlook on the web and Outlook mobile, in new messages and replies. Users can still type below it, and they cannot silently replace the locked disclosure. Every change is versioned per template, so you can roll a group back to the previous signature.
Is this an email signature manager for Office 365 only?
No. The same account manages Google Workspace to the same depth, in the same template sets, which is why companies running both platforms after an acquisition buy one product rather than two.
Does it work with the new Outlook and Outlook on the web?
Yes. The signature is on the mailbox, so the new Outlook, Outlook on the web and Outlook on Windows and Mac all present it. The client-by-client detail is on the Outlook signature manager page.
What about Teams, shared mailboxes and aliases?
Shared mailboxes and send-as aliases take a template like any other mailbox and count once against your band. Teams messages are not email and carry no signature.
Does it break our transport rules?
No. AutoSignature writes signatures, it does not create or modify mail flow rules. If you keep a disclaimer rule, it keeps working exactly as it does today.