How to Create and Enforce Common Signature in Office 365

Microsoft 365 admins can create a common signature and a disclaimer so that every user within their organization has the same and consistent signature. This practice is more common in large companies and enterprises. Without a common signature, an employee can create their own with fonts or colors of their choice.

If you would like to create a common signature in Office 365 for your company, follow these simple instructions.

8 Easiest Steps to Create a Common Signature and Disclaimers in Microsoft 365

Step 1: Sign in to Microsoft 365 Admin Center

Go to https://admin.microsoft.com and log in with your admin credentials.

Step 2: Open Exchange Admin Center (EAC)

Under Admin centers, click on Exchange. This will open the Exchange Admin Center in a new tab.

Step 3: Go to Mail Flow

In the EAC dashboard, go to the Mail Flow section from the left-hand menu. Click on Rules to view existing mail flow rules.

Step 4: Create a New Rule

Click the “+” (plus) icon and select “Add a rule”. Choose “Apply disclaimers” from the dropdown options. This option allows you to create an organization-wide email signature.

Step 5: Configure Rule Conditions

Name your rule — e.g., Company Email Signature.

Under Apply this rule if, select:

• The sender is located → Inside the organization
• Or choose Apply to all messages if it should apply to every email.

Under Do the following, select Append the disclaimer.

Click Enter text and paste your HTML or plain text signature.
Include elements like:

• Company name and logo
• Employee name (dynamic via AD attributes)
• Contact details
• Legal disclaimer or tagline

Set a fallback action: Choose Wrap so the message is still delivered even if the signature can’t be appended.

(Optional) Add exceptions for certain senders, recipients, or attachments.
Click Next to continue.

Step 6: Set Rule Settings

Under Rule mode, choose Enforce to turn on the disclaimer immediately, otherwise, choose Test with Policy Tips or Test without Policy Tips.

Set the Severity level based on your organization’s policy.

Specify when the rule should be active by selecting Activate this rule on and Deactivate this rule on with the desired dates.

Enable Stop processing more rules if you want this signature rule to take priority over others.

(Optional) Select Defer the message if rule processing doesn’t complete to ensure proper rule execution in case of processing delays.

Step 7: Review and Finalize the Rule

Once the new rule has been processed, select Finish.

Step 8: Rule has been created

Ensure the rule is enabled and appears in the list.

Tip: Always test your setup by sending internal and external test emails to verify signature formatting and attribute rendering before full enforcement.

Limitations of Organization-Wide Signatures in Microsoft 365

Microsoft 365 has some limitations when managing company-wide email signatures:

• Signatures can’t be placed directly under replies or forwards.
• Server-side signatures don’t show up in Sent Items.
• Embedded images aren’t supported.
• Empty lines from missing user details can’t be removed automatically.

For advanced features like dynamic placement and image embedding, consider using a third-party signature management tool.

For PowerShell instructions, see Organization-wide disclaimers, signatures, footers or headers in Exchange Online.

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Frequently Asked Questions

1. How do I test company-wide signature before deployment?

Recommended Test Checklist:

By following these steps, IT admins can test company-wide signatures thoroughly before deployment to avoid branding inconsistencies or rule conflicts during organization-wide enforcement.

2. How do I detect duplicate or chained disclaimers?

Send test emails and replies between accounts. If the disclaimer repeats, check Exchange Admin Center → Mail Flow → Message Trace to see if the same rule ran multiple times.

3. How do I stop disclaimers from repeating in email threads?

Edit your mail flow rule and add an “Except if” condition — e.g., “The subject or body includes this text…” — with part of your disclaimer text.

4. Should I stop other rules from applying after the disclaimer?

Yes. Enable “Stop processing more rules” so other mail flow rules don’t reapply the disclaimer.