您无法检查Email ContentProvider的内容，因为这需要只有系统应用程序才能请求的权限.在 AndroidManifest for Email 中定义:

You cannot check the content of the Email ContentProvider, because this requires a permission that only system apps can request. This is defined in AndroidManifest for Email:

<permission
    android:name="com.android.email.permission.ACCESS_PROVIDER"
    android:protectionLevel="signature"
    android:label="@string/permission_access_provider_label"
    android:description="@string/permission_access_provider_desc"/>
…
<application>
    …
    <!-- This provider MUST be protected by strict permissions, as granting access to
         it exposes user passwords and other confidential information. -->
    <provider
        android:name=".provider.EmailProvider"
        android:authorities="com.android.email.provider;com.android.email.notifier"
        android:exported="true"
        android:permission="com.android.email.permission.ACCESS_PROVIDER"
        android:label="@string/app_name"
        />
    …
</application>