A consistent email signature helps your business look professional, reinforces your brand and ensures important contact or legal information appears on outgoing messages.
Microsoft 365 offers two main ways to manage email signatures: centrally through Exchange Online mail flow rules or individually within each Outlook mail client. Here is how they differ and how to choose the right approach.
What is a Microsoft 365 mail flow disclaimer?
A mail flow disclaimer is text or HTML automatically added to an email while it passes through Exchange Online. Despite the name, it can contain a complete company signature, including:
- The sender’s name and job title
- Telephone and email details
- Company branding and website links
- Registered business information
- A legal or confidentiality notice
Because Exchange adds the content after an email is sent, it can cover messages from Outlook desktop, Outlook on the web, mobile devices and other connected email applications.
How do you create an email signature using a mail flow rule?
You will need suitable Microsoft 365 administrator permissions.
- Sign in to the Exchange admin centre.
- Open Mail flow, followed by Rules.
- Select Add a rule and then Apply disclaimers.
- Give the rule a clear name, such as “External company signature”.
- Choose when the rule should apply. For example, select messages sent to recipients outside the organisation.
- Under the action, select Apply a disclaimer to the message and append a disclaimer.
- Enter the signature using plain text or HTML.
- Select a fallback action for messages that cannot be modified, such as encrypted emails.
- Add any necessary exceptions, review the rule and test it before fully enabling it.
Microsoft supports directory placeholders such as %%DisplayName%%, %%Title%%, %%Phone%% and %%WindowsEmailAddress%%. These allow one template to display information belonging to the individual sender, provided their Microsoft 365 profile is kept up to date.
Microsoft provides further technical details in its guide to organisation-wide signatures and disclaimers.
How is this different from setting a signature in Outlook?
An Outlook signature is created within the user’s email application. In new Outlook and Outlook on the web, users can normally find this under Settings > Accounts > Signatures. Classic Outlook uses New Email > Signature > Signatures.
The biggest difference is where the signature is applied.
| Mail flow disclaimer | Outlook signature |
|---|---|
| Managed centrally by an administrator | Usually managed by each user |
| Applied after the message is sent | Visible while the email is being written |
| Can cover different mail clients and devices | May require setup in more than one client |
| Helps enforce consistent branding | Gives users more flexibility |
| May appear at the bottom of the full conversation | Can appear directly beneath the latest reply |
| Relies on accurate directory information | Information is entered directly into the signature |
Microsoft’s Outlook signature instructions also explain how users can choose different signatures for new messages, replies and forwards.
Which Microsoft email signature option is best?
Mail flow rules are useful when a business needs central control, reliable legal wording or consistent branding across many users and devices. However, users cannot normally see the server-added signature while composing their message, and its position in long email conversations may not always look natural.
Client-based Outlook signatures offer better placement and allow the sender to preview the finished email. The drawback is that users may change the design, enter incorrect information or fail to configure the signature on every email client they use.
Some organisations use a combined approach: Outlook provides the visible personal signature, while a mail flow rule adds a short legal footer or required company information. Rules must be carefully scoped to prevent duplicated content.
Frequently asked questions
Do mail flow signatures work on mobile emails?
Yes. As Exchange Online applies the signature during delivery, it can cover messages sent from mobile devices as well as desktop and web applications.
Can a mail flow signature use each employee’s details?
Yes. Exchange Online supports placeholders that retrieve information from the sender’s Microsoft 365 directory profile. Missing or outdated profile information can lead to incomplete signatures.
Can users edit a mail flow disclaimer?
Not before sending. The signature is added centrally after the message leaves the user’s email client.
Why does the signature appear at the bottom of an email chain?
Mail flow rules modify the message during transport and cannot reliably position a signature directly beneath the newest reply. If precise placement is essential, an Outlook signature or specialist signature-management platform may be more suitable.
Need help managing Microsoft 365 email signatures?
Cloud Digital can help your business configure Microsoft 365, Exchange Online mail flow rules and professional email signatures that support consistent branding across your organisation.
Contact Cloud Digital or call 01202 006064 to discuss your requirements.
