Not sure if this is the right part of the forum, I can't see a better place to put it. I'm using Mac Mail 5.3 on OSX 10.7. It's an IMAP connection over secure ports and generally works great. What I find randomly is that something happens and the mail needs to be resync'd. If i click on a folder then I can see the emails and they all disappear then must be downloaded again from the mail server. The emails are never lost as they server keeps them. Every folder that is clicked does the same thing once after the 'hiccup' has happened, folder shows the emails, then wipes them all, then shows the headers, and then slowly fills in the bodies as they are downloaded. It will only do it once per folder after it's happened, after its downloaded again it will be fine for that folder. If I switch the wifi off then I can view the cached emails fine. And when I go back online, as soon as I look at a folder again it goes to redownload them. It's as if the mac's cache is somehow out of date and it wants everything downloaded again. I share the account with a outlook on a PC. It never has the issue, it will show the emails there when it happens on the mac. The emails don't move from the server I've checked before with the web app for viewing them. I'm not sure if the connection to the server is interrupted and the mail program can't cope at the wrong point. It's very annoying when the email needs to take another hours to redownload.