<TextBlock >
    <Hyperlink NavigateUri="{Binding Url, ElementName=root}" >
        <TextBlock Text="{Binding Text, ElementName=root}" />
    </Hyperlink>
</TextBlock>

public static readonly DependencyProperty UrlProperty = DependencyProperty.Register("Url", typeof (string), typeof (LinkTextBlock));
public string Url
{
    get { return (string) GetValue(UrlProperty); }
    set { SetValue(UrlProperty, value); }
}
public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof (string), typeof (LinkTextBlock));
public string Text
{
    get { return (string) GetValue(TextProperty); }
    set { SetValue(TextProperty, value); }
}

<Controls:LinkTextBlock Text="{Binding Email}" Url="{Binding Email}" />

<TextBlock >
    <Hyperlink NavigateUri="{Binding Url, ElementName=root}" >
        <TextBlock Text="{Binding Text, ElementName=root}" />
    </Hyperlink>
</TextBlock>

<TextBlock  Text="{Binding Text, ElementName=root}">
    <Hyperlink NavigateUri="{Binding Url, ElementName=root}" />
</TextBlock>