How To Have Separate Email Signatures for Internal and External Emails

There are only two available options: setting a default signature For New Messages and setting one For Replies/Forwards. If it were a matter of needing the different signature for time of day, you could create an "internal sig" and "external sig" and just switch the default, but other than that, there is no explicit way to set one signature to internal domains and another one for external domains.

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Hi @Brian Cooper ,
You could create two signatures, but you could not automatically add signatures for internal and external emails. You could manually select the signatures you want to add when you send the email.
Refer to: Create and add a signature to messages and Change an email signature

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Thought it's a dead thread, but I've seen new comments popping up, so I'm going to jump in.

With built-in tools, there's no way to automatically apply different email signatures for internal and external email, so the only thing you can do is design email separate email signatures in Outlook and apply diffferent versions manually.

Another option is using third-party email signature management tools - they allow you to centrally manage email signatures for everyone and add different versions for internal and external email (they can be applied based on more specific conditions as well. There are multiple products that can do this, you can find them, for example, on the Microsoft Appsource listing: https://appsource.microsoft.com/en-us/