Within Windows reports that Yahoo's IMAP server caused the Windows Phone data usage overages

Last week, I tore apart Windows Phone feedback packets to determine the feature’s role in the Windows Phone 7 data usage saga. I didn’t find anything of significant worry there, so I moved onto the next suspected culprit in the list: Yahoo.

Sniffing out IMAP packets to and from a Windows Phone isn’t as straight forward as it sounds. Microsoft’s IMAP4 implementation is very aware of the STARTTLS extension emitted by IMAP servers and switches to encrypted communication as soon as its detected, kinking the sniffing operation. (Worse, there’s no official UI for forcing clear-text communication.) To workaround this, I wrote a quick nodejs script to strip IMAP connections of the STARTTLS bit and passed them on to their destination.

  Yahoo confirmed culprit in Windows Phone data usage overages