Have several of our company's officers with iPad 2 (Version 5.1.1 on all). The iPads sync up with an Exchange 2010 sp1 server for email. What the users see is the email comes in and after a few moments, the emails that have come in will dissappear. They then can no longer be found on either the iPad or in Outlook (v2010) in any folder or deleted items.
I have searched the forums and have run across many people with the same issue, but so far no solutions that have worked for us. On the iPads, the "Mail Days to Sync" are set to No Limit. The Outlook client is using an OST file instead of PST, and going through the settings it's not set up to take emails off the server. I know it's not a deleting issue since we have the Exchange server itself limiting the user from "true" deletions. I have found 1 of the 3 users that is experiencing this problem also have an iPhone 4 (also version 5.1.1). However when he has his iPad with him, email for the Exchange account is turned off.
This does not happen every time but quite randomly and without any rhyme or reason that I can determine. I have actually witnessed the emails come in and then *poof*, are gone. Exchange accounts do not have rules set up and archive is set to only archive items older than 6 months. I have contacted Apple support and they were "less" than knowlegeable and even stated that "this is not a known issue" despite several posts and hence would not help unless we paid for support (obviously).
I hope someone has some type of solution or something that I can take a look at to see if there is a setting or something that I am missing. For all I can tell, it should be working as it's supposed to. I can scratch out Exchange since the only users affected are the ones using iPads. I can provide any other details if needed.