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App Setup » Develop » Custom Settings » Manage [S4S Settings]
Figure 19: Manage the S4S Settings
Create or Edit the "DefaultSitecoreUsernameField" custom setting.
Figure 20: The "DefaultSitecoreUsernameField" Custom Setting
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You can change the Setting from "Name" to "Email" (or another identity). This will cause the default Contact Sitecore user name to be the email address rather than the Name.
Figure 21: Altering the default DefaultSitecoreUsernameField setting
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