Mailtiv / Blog

How to add the same signature for all users in Microsoft 365

Updated 4 November 2026 by the Inthouse product team

The short answer: if one plain block of text is enough, a mail-flow rule in the Exchange admin center does the job. If you want a signature with each person's own name, title, phone and photo, visible while they write and able to change by department, you need a signature tool that works as an Outlook add-in. Both ways are explained step by step below.

Way 1: a signature with a mail-flow rule (Exchange admin center)

Microsoft 365 lets you add text to outgoing email on the server. The feature is called a "disclaimer", but many companies use it for signatures.

The general steps:

1. Open the Exchange admin center.
2. Go to Mail flow → Rules and add a new rule.
3. Choose Apply disclaimers.
4. Set which messages the rule applies to (for example, only email sent outside the organization).
5. Enter the signature as HTML, choose a fallback action and save the rule.

This costs nothing extra and works for every mailbox from one place. But it has limits:

• The signature is added after sending. People don't see their signature while writing; it's added as the message passes through the server.
• The signature can end up at the bottom of the thread. The rule adds the text at the end of the message, so in a long conversation the signature may sit below the quoted older messages rather than right under the new reply.
• Images and design are limited. Complex HTML designs, logos and photos may not look the same for every recipient.
• Personal and department signatures are hard work. Each department or campaign needs its own rule, and all of them need keeping up to date.

Way 2: a signature with an Outlook add-in

With this approach the signature is added inside Outlook when someone starts a new email, replies or forwards. They see the signature while writing, and the email is sent as it is; it doesn't pass through another server.

This is how Mailtiv works:

• Admins design signatures in the Mailtiv portal.
• The Mailtiv add-in for Outlook is deployed to all users once, from the Microsoft 365 admin center.
• The add-in reads each person's Microsoft 365 profile and fills in the signature with their name, title, department, phone numbers, office address and photo.
• The signature is added in Outlook for Windows (new and classic), Mac, Outlook on the web, iPhone and Android. On phones, meeting invites don't get a signature.

So "the same signature for everyone" really means "the same design for everyone, with each person's own details". For the setup steps, see Set up Mailtiv.

Department, group and company signatures: which one wins?

One design isn't enough for most companies: sales may want a campaign banner, legal an extra note. In Mailtiv each person still gets one signature, chosen in this order:

1. If they're in a signature group, they get that group's signature.
2. If not, and there's a signature for their department, they get that.
3. Otherwise they get the company signature for their email domain.

While a campaign is running, it replaces the signature of the people it targets; when it ends, everyone goes back to their usual signature. Details are in the Portal guide.

Keep profile details up to date in Microsoft 365

Whichever way you choose, the details in the signature come from the user profile in Microsoft 365. So:

• Check the title, department and phone fields in Microsoft 365 regularly. In Mailtiv, the department field also decides which department signature someone gets.
• When someone's title changes, update the profile, not the signature. Mailtiv picks up the change; profile changes can take a few hours to reach the signature.
• Ask people to remove their own Outlook signatures, or an email may show two.

Which one should you choose?

• Mail-flow rule: one plain block of text, a small number of users, no images or personal details needed.
• Outlook add-in: personal details, department and group signatures, dated campaigns, and a signature people can see while they write.

For a detailed comparison of the approaches (mail-flow rules, server-side signature services and Outlook add-ins), see Ways to manage email signatures.

Frequently asked questions

Can I add a signature for everyone in Microsoft 365 for free?

Yes. In the Exchange admin center you can create a mail-flow rule with the Apply disclaimers action. The signature is added on the server after sending; people don't see it while writing, and design options are limited.

How does each employee's own name and title appear in the signature?

The details come from the Microsoft 365 profile. The Mailtiv add-in fills in the signature with each person's own profile details; if something is wrong, updating the profile in Microsoft 365 is enough.

Can departments have different signatures?

Yes. If you set up a signature for a department in Mailtiv, the people in that department get it. The department comes from the Department field in Microsoft 365. A signature group or a running campaign takes priority over the department signature.

What should I do if an email shows two signatures?

Usually the person's own Outlook signature is also switched on. Ask them to remove it, or to choose "(no signature)" for new messages and replies.