I'm using a 3rd generation iPad running under iOS8.1.3 (12B466) and iOS's default Mail app. All apps are up to date. I have twelve email accounts, six with me ISP and six with gmail and all bar one are POP accounts. When I awoke this morning, the accounts on my iMac showed a handful of unread overnight emails. The downloads must have happened between 02:00 and 07:00 GMT/UTC, the time I last checked my email and the time I woke this morning, although I doubt that those times are relevant. The several gmail accounts on the iPad showed, quite correctly, one overnight email and my ISP's accounts showed ... ... wait for it ... ... you'd better sit down ... ... OK, here goes ... ... 12,489 unread emails! This amounts, approximately, to 4,000, 4,000, 100, 500, 3,900 and 0 in each of my ISP's accounts. As I said above, the same accounts on my iMac (Yosemite and Apple's Mail) were "correct". Firstly, why might this have happened? Secondly, how can I delete them all other than by doing it one by one thereby developing severe digital stress on my right index finger? Thirdly, how can I stop this happening again? Help, please!