Unread emails being marked automatically marked as read?

My Yahoo mail is marking messages as Read before I have read them, and I'm missing out on important messages. I have changed settings to say Mark as Read - Never, and this has not helped. It happens across all my devices including the web browser on my laptop, work PCm, and my iPad and iPhone. It has only started happening recently (approx 2 weeks). This does not happen with other emails that I view on the iPad and iPhone (e.g. Exchange account). I have changed passwords, and don;t think the account has been hacked.

  • Why do my emails delete themselves automatically? Some but not all emails I received are deleted automatically. They are not spam or junk, but they are no where to be found - not in the trash/deleted messages, inbox, junk or spam. I know I received them because they show on the iPhone notification screen, but when I click on them, they are not there at all. Can't find it on computer, yahoo web mail, or iPhone hand set. This has happened since about a week ago. Any idea why and how to fix this?
  • Why do my emails automatically get deleted after a certain amount of time? My emails always get deleted after a certain time on my iphone?! It makes me made because i have colleges emailing me on my phone and sometimes when i need the emails they aren't there anymore. I tried making a folder and putting the college emails in there and they still get deleted! Help how can i stop my emails from being deleted? I have an iphone 5 and my email is with outlook/hotmail.
  • Why aren't my emails being sent? On my hotmail, I can receive emails but when I send them I get a delivery failure email that the email can't be sent even if I'm sending the email to a valid address. I can't from my iPhone or even my laptop& pc. what's wrong with it? how do I get my emails to send. * I use hotmail to send emails. It's my main account. sorry if it's the wrong category, its the closest.
  • Read messages on my iPhone sometimes show up as unread messages on my Mac? - 1 I'm talking about email messages. I have my accounts hooked up to iCloud, so if I read an email on my iPhone or Mac, it should count it as read on the other device. It has worked, but sometimes it doesn't. What can/should I do?