I tried links like this - http://mail.yahooapis.com/ya/download?mid=2_5_22_1_10098_AKgk5C4AAAdKUqnjhAAAAC9hbkI&pid=1.2&fid=%40S%40Search&inline=1&appid=GenericOAuth
But Yahoo answers "Sorry, the page you requested was not found."
On HTTPS request with the same url Yahoo replied to me with "The page cannot be displayed" and HTTP CODE = 502, Cannot find server.
Any suggestion how to download attachments?
It doesn't work because you are using the search fid. If you need to search you should use the ymail.search table in YQL. (In other words don't use SearchMessages API). Second you need to do the download with the right folder.
Solved - The problem was with OAuth headers.
in Yahoo! Mail Web Services API