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Microsoft Outlook Signature Research

Project Description

We need to investigate where and how signature properties are stored in Microsoft Outlook, research and suggest options how to copy an Outlook signature to a new Outlook profile.

Completion Notes

Outlook research and testing environment was as follows:

Outlook 2013 signatures are configured on the New Email - Signatures dialog. Start composing a new email using the New Email command on Outlook ribbon.

New email icon in Microsoft Outlook 2013
New email icon in Outlook 2013

When new email window appears, click the Signature icon on the ribbon and use the Signatures... option.

Signature icon in Microsoft Outlook 2013 new email window
Signature icon in Outlook 2013 new email window

Clicking the Signatures... icon in Outlook reveals the following options:

Signature command options in Microsoft Outlook
Signature command options in Outlook

Location of Signature Files

Our research showed that Outlook signatures are located in files in %APPDATA%\Microsoft\Signatures

Location of Microsoft signature files
Location of Microsoft signature files

As you can see, there are .htm, .txt, and .rtf files in there for each one.

Signatures in a New Outlook Profile

When we create a new Outlook profile for a user, signature files are still in the above mentioned location, available for use in a new message (New Email - Signature command).

The problem is that in a new profile there is no default signature on a new message. User must specifically select a signature.

In other words, creating a brand new profile gets us no default signature on a new message. A client who ordered this research intended to create Outlook profiles programmatically in a way that user default signature is set. It is, therefore, important to determine how to do it.

Location of Outlook Profile Properties

Our research has shown that the profile attributes are stored in local registry. For example, for a profile named Outlook the key name is:


The last part in key name is a profile name. See

Which profile value is responsible for a default signature in a new message? The New Signature value in one of the registry keys for a MAPI profile, for example:

Key: HKCU\Software\Microsoft\Office\15.0\Outlook\Profiles\Outlook\9375CFF0413111d3B88A00104B2A6676\00000002

Value: New Signature
Value: Text containing the file name of the signature to use. For example, if you have a signature file named "Alternative signature" then the value may contain this text, and %APPDATA%\Microsoft\Signatures will also contain the following:

Copying an Existing Outlook Profile

Copying an existing profile gets as a a copy of registry subset with New Signature value present. Therefore, when composing a new message in such profile we do have a default signature already.

Using an Existing Signature in New Outlook Profile

If we want to use an already existing signature as a default signature on new messages, we can insert the New Signature value into the registry.

Another option is, apparently, inserting a MAPI property (not sure which one) for a new signature via die-hard MAPI method of profile manipulation.