This past Wednesday, Microsoft identified a 3G data glitch that inflated data throughput on Windows Phone 7's as a problem with Yahoo mail. Phone owners using Yahoo's own technology to fetch mail messages experienced as much as 25 times the normal data transfer quantities. The bug had first been spotted several weeks ago, but only now has been singled out as Yahoo Mail-based (despite the search engine's protests to the contrary).
Now it appears that iPhone users getting their mail through Yahoo's push technology are susceptible to the same glitch — shortly after Yahoo insisted that iPhones (as well as Blackberries, Android and Symbian handsets) were immune.
Many WP7 owners are steamed at Microsoft for not revealing the problem sooner, as it could leave them open to unexpected data overage fees. Neither Apple nor Yahoo have commented on the latest findings, but if you're an iDevice owner with Yahoo mail, consider reducing your automatic mail checks or switch to manual-checks-only mode.