How to set a company-wide email signature in Microsoft 365

To set company email signature Microsoft 365 wide, an admin creates an Exchange mail flow rule: Mail flow, then Rules, then Add a rule, then Apply disclaimers, with the action set to append your text to every message. Microsoft calls organization-wide signatures “disclaimers”, whatever they contain. The steps below follow Microsoft’s admin guide to organization-wide signatures and its Exchange Online page on disclaimers, signatures, footers or headers, both read in October 2026.

What a mail flow rule does, and does not do

A mail flow rule (also called a transport rule) runs on the server as a message leaves or enters your organization, and adds HTML or plain text at the top or the bottom. It is good at a single block of identical text: a legal line, an address, a registration number.

It is not the same as the signature a person sets in Outlook. Microsoft’s Exchange page notes that users can apply signatures to their own outgoing messages in Outlook or Outlook on the web, and points to a separate page for that. If you want those steps, see adding a signature in Outlook on the web. A rule is a separate layer from personal signatures.

Before you start

A few decisions come first when you set company email signature Microsoft 365 wide.

• You need to be assigned permissions for the Mail flow feature in Exchange Online. Microsoft’s Exchange page points to its feature permissions article to see exactly which role.
• Microsoft estimates about 7 minutes for each procedure.
• Decide whether the text goes on all messages, or only on messages sent outside your organization. By default, mail flow rules apply to both incoming and outgoing messages, so a “send to outside only” condition matters.
• Prepare the text. It can include HTML tags and inline CSS, per the Exchange page.

How to set company email signature Microsoft 365 wide: the steps in the admin center

These follow Microsoft’s admin guide for a rule that applies to all messages.

1. Sign in to the Exchange admin center. You can also reach it from the Microsoft 365 admin center by selecting Show all, then Exchange under Admin centers.
2. In the left navigation, expand Mail flow, then select Rules.
3. On the Rules page, select Add a rule, then Apply disclaimers.
4. On the Select rule conditions page, enter a Name for the rule.
5. Under Apply this rule, select Apply to all messages. For outside recipients only, Microsoft’s Exchange page uses The recipient then is external/internal, then Outside the organization.
6. Under Do the following, choose Apply a disclaimer to the message and append a disclaimer.
7. Select the Enter text link, type the disclaimer text and select Save.
8. Select the Select one link, choose a fallback option (see below) and select Save.
9. Optionally set an Except if condition, then select Next.
10. On Set rule settings, choose a Rule mode, a Severity and optional dates, then select Next.
11. Review, select Finish, and when it finishes saving, select Done.

Leave Match sender address in message at its default of Header. Microsoft says it is not relevant for a rule that applies to all messages.

Pick the rule mode carefully

Testing is how you set company email signature Microsoft 365 rules without surprising anyone. Under Rule mode, Enforce turns the rule on immediately. The other two choices, Test with Policy Tips and Test without Policy Tips, let you check the result first. The Exchange page recommends testing all mail flow rules before setting them to Enforce, and with the no-Policy-Tips option the results are logged without the disclaimer being added.

Fallback options

Some messages cannot be modified, for example encrypted ones. The fallback tells the rule what to do then.

Option	What happens
Wrap	A new message is created, the original goes in as an attachment, and the disclaimer is added to the new message. This is the default.
Ignore	The rule is skipped and the message goes out without the disclaimer.
Reject	The message is returned to the sender as a non-delivery report.

Microsoft warns against using Wrap in rules that affect incoming messages from external senders, because it interferes with Safe Attachments scanning. It recommends Reject there. For an outgoing signature rule, check whether Wrap suits you: if the wrapping fails, the original message is not delivered and the sender gets a bounce.

Avoid a pile of repeated disclaimers

Without a guard, a long email thread can collect your footer on every reply. The Exchange page’s fix is an exception: under Except if, choose The subject or body, then Subject or body matches these text patterns, and enter a distinctive phrase from your disclaimer. The disclaimer is then added only once, to the original message.

Fill in names and numbers with tokens

The disclaimer text supports tokens that pull values from the sender’s directory entry. The Exchange page lists them all. A few useful ones:

Token	Fills in
%%DisplayName%%	The sender’s display name
%%Title%%	Job title
%%Department%%	Department
%%Phone%%	Phone number
%%MobilePhone%%	Mobile number
%%Company%%	Company
%%WindowsEmailAddress%%	Email address

Microsoft’s admin page adds a catch. Rules skip lines that contain variables they cannot update. If a line uses %%Phone%% and a user has no phone number in the directory, the whole line disappears. The data your signature draws on is only as good as your directory.

The limits, in Microsoft’s words

If you set company email signature Microsoft 365 rules, expect these limitations, which the admin page lists:

• You cannot insert the signature directly under the latest reply or forward.
• Users cannot see server-side signatures in their Sent Items folders.
• You cannot embed images in the signature.
• Lines with variables the rule cannot fill are skipped.

On images there is a nuance that the two pages together make clear. The admin page says you cannot embed images. The Exchange page says disclaimer text can include an image added with the image tag, and its PowerShell example points to a logo hosted at a web address. In practice, that means a linked, hosted image is possible and a pasted-in, embedded one is not. Check it on a test recipient, since mail apps that block remote images will not display it until the reader allows them.

Check that it worked

Microsoft’s own list of checks is sensible. Send yourself a plain-text email and an HTML email that match the rule and see that the text appears as you intended. If you added a repeat guard, forward a test message to yourself and confirm there is no second copy. Then send some messages that should not get the footer and confirm they do not.

When a rule is not enough to set company email signature Microsoft 365 wide

A rule gives every message the same bottom block. Tokens fill in text, but Microsoft’s pages describe no per-person image such as a headshot, and the block cannot sit directly under the latest reply. One way to split the work is to let the rule carry the legal line and let people carry their own contact block.

emailfooter covers the second half. The company fixes the layout and logo, and each person fills in their own details and follows numbered steps to install it in their mail app. It does not write into mailboxes, there is no auto-push, and it is English-only for now. The legal text below can live in either place, but not both, or you will print it twice. Here is a person block with a notice line, drawn by emailfooter:

Executive layout with a notice line. The company and person are made up.

For wider context, read about company email signatures and Microsoft 365 signature management tools. Google Workspace has its own approach, covered in setting signatures for all users in Google Workspace.

Frequently asked questions

How do I set company email signature Microsoft 365 for outside recipients only?

In the rule conditions, choose The recipient, then is external/internal, then Outside the organization. By default a rule applies to incoming and outgoing messages.

How do I set a company email signature in Microsoft 365?

Create a mail flow rule in the Exchange admin center: Mail flow, Rules, Add a rule, Apply disclaimers. Choose Apply to all messages and append a disclaimer.

Can I put a logo in a Microsoft 365 company signature?

Microsoft’s admin page says you cannot embed images. Its Exchange page shows disclaimer text with an image tag pointing at a hosted file, so a linked image can work.

Why is the signature not under the latest reply?

Microsoft lists this as a limitation. The server-side text cannot be inserted directly under the latest reply or forward.

Can users see the company signature in Sent Items?

No. Microsoft says users cannot see server-side email signatures in their Sent Items folders.

Do I need PowerShell?

No. The Exchange admin center steps work without it. PowerShell is an alternative: the Exchange page documents the New-TransportRule command.