Which Method Fits Your Organization?
Exchange Online has no email signature page for admins. The mail flow rule feature adds the email signature. Microsoft names it a disclaimer.
| Method | Scope | Cost | Use case |
|---|---|---|---|
| Mail flow rule | Organization wide | Free | Same signature for all senders |
| PowerShell rule | Organization wide | Free | Scripted setup |
| Outlook settings | One user | Free | Personal signature |
How does a Mail Flow Rule Add a Signature?
Method #1: Mail Flow Rule in the EAC (Free, Admin)
Who it suits. Admins who add one signature to outgoing mail. Extra application. None.
- Open the Exchange admin center at admin.exchange.microsoft.com.
- Go to Mail flow and select Rules.
- Select Add a rule and select Apply disclaimers.
- Enter a unique name and set the condition, for example Outside the organization.
- Select Apply a disclaimer to the message and select append a disclaimer.
- Enter the email signature text and select a fallback action.
- Set the rule mode and select Finish.
The Microsoft disclaimer page states that append is the default. Prepend adds the text to the top of the message.
Which Tokens Fill the Signature?
The disclaimer text takes tokens that read values from the sender.
| Token | Value |
|---|---|
| %%DisplayName%% | Sender name |
| %%Title%% | Position title |
| %%Department%% | Department |
| %%Company%% | Company |
| %%Phone%% | Phone number |
| %%MobilePhone%% | Mobile number |
| %%WindowsEmailAddress%% | Email address |
The text can use HTML tags and inline CSS. Images use the IMG tag.
How do You Create the Rule With PowerShell?
Method #2: PowerShell Transport Rule (Free, Command Line)
Who it suits. Admins who script the setup. Extra application. Exchange Online PowerShell.
Connect-ExchangeOnline
New-TransportRule -Name "External Signature" -SentToScope NotInOrganization -ApplyHtmlDisclaimerLocation Append -ApplyHtmlDisclaimerText "<p>%%DisplayName%%<br>%%Title%%, %%Department%%<br>%%Phone%%</p>" -ApplyHtmlDisclaimerFallbackAction WrapThe cmdlet matches the EAC rule. The ApplyHtmlDisclaimerLocation parameter sets append or prepend.
What do the Fallback Options do?
The fallback applies when the rule cannot edit a message, for example an encrypted one.
- Wrap attaches the original message to a new message with the signature. Wrap is the default.
- Ignore delivers the message without the signature.
- Reject returns the message to the sender in an NDR.
Microsoft states that rules for incoming mail from external senders use Reject, because Wrap interferes with Safe Attachments scanning.
Add an exception that matches unique signature text. The signature then stays off replies that quote it.
How do Users Add a Personal Signature?
Method #3: Outlook Signature Settings (Free, per User)
Who it suits. Users who want a personal signature. Extra application. New Outlook.
- Select Settings, then Accounts and Signatures.
- Select Add signature and enter a name.
- Type and format the email signature.
- Tick the boxes for new messages and for replies and forwards.
- Select Save.
The Microsoft signature page states that a signature can contain text, links and pictures. Users can create several signatures, for example one for internal mail.
Microsoft does not describe how personal signatures interact with the Exchange Online disclaimer.
How do You Test the Rule?
Set the rule mode to Test without Policy Tips first. Outlook logs the matches and adds no text.
Send plain text and HTML messages that match the rule. Forward one of them to confirm that no second signature appears. Send a message that should not match.
Move the rule to Enforce after the tests. Read the Exchange Online migration checklist for the other setup tasks.
Frequently Asked Questions
How do You Set an Email Signature in Exchange Online?
Create a rule in Mail flow with the Apply disclaimers option and append the signature text.
Why does Microsoft Call It a Disclaimer?
Exchange Online adds organization wide text as a disclaimer. The text can contain a signature.
Can the Signature Use Sender Details?
Yes. Tokens like %%DisplayName%% and %%Title%% read the sender values.
Does the Signature Appear at the Top?
No. Append is the default and adds the text to the bottom. Prepend adds it to the top.
How do You Avoid a Repeated Email Signature in Replies?
Add an exception that matches unique text from the email signature.
Which Fallback should You Choose?
Wrap is the default. Use Reject for incoming external mail rules.
Can Users Add Their Own Email Signature?
Yes. Users create signatures in Outlook settings.
Author's Verdict
Use a mail flow rule for one email signature across the organization.
Add personal signatures in Outlook settings for individual needs.
Key Takeaways
- Microsoft names an organization wide signature a disclaimer.
- Tokens fill sender details.
- Test the email signature rule before Enforce.
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