Add download possibility from email attachment in Android Webview

I currently have an app that opens an email account (GMX, Live Mail) using a WebView in Android. However, it is not possible to download any attachments. I would like them to be downloaded as if you are using a browser. When downloading an attachment the attachment is first scanned for virusses etc. by the GMX/Live Mail server. So, it is not a 'direct' URL pointing to the file (not: xxx/xxx/[login to view URL]). To verify how this works, you can obviously see the process by downloading an attachment from one of the above mentoined email accounts yourself. Note that I already have a working application - it is just the downloading feature that that needs to be added. If you have any questions regarding the project, please let me know.