I have 2 users reporting that, on random occasions they have noticed random emails disappear out of their email (inbox or subfolder) then reappear later. It's not all emails in the inbox or folder, just one or two. Users swear that the message was in their inbox.

For example,  Sally receives an email from Bob about a report they are working on.   Sally reads the message and leaves it in her inbox.   A few days later Sally searches for that message again and search cannot find it, nor can she find it scrolling back thru her inbox.  But if she closes outlook and reopens outlook and tries again, she finds the message.  

We are on Outlook 2013, Exchange 2010 (sp3, RU10), Outlook is running with cache mode enabled and some of these users probably have larger *.ost files. 

Reproducing this issue is impossible because it is random.  And catching it when it happens to run tests or take a look is just as hard because when the user is searching for those messages, they are usually in a rush and don't report the issues until after they have restarted outlook, found the missing email and taken care of their work before reporting it to IT as an afterthought.

Now, I know, I've had the occasion where I've looked for something in my email that I know I saved and can't find it, but I try a second time and it's there - and I usually chalk up the oversight to stress and being busy.   But these users swear up and down that the messages are "not there" and then reappear later.

Hi,

Since this issue happens randomly, it's hard to tell the exact root cause of the issue. However, we can use the following method to narrow down the cause.

Do the users have any third-party add-ins installed with Outlook? If any, please go to File > Options > Add-ins and disable suspicious add-ins to see if the issue will happen again.

Do the users have their email accounts synced with any mobile devices? If so, please try disable the synchronization on the mobile devices and check if this issue will continue.

We can also try recreate the OST files in case the data file is corrupt.

Regards,

Steve Fan
TechNet Community Support

I have disabled the Symantec end point protection add-in which is the only one she has that would be questionable as to possible issue.   The other add-ins she has are Microsoft, SharePoint and WinZip.   (the Symantec is also covered with a server side scan as well as other controls as emails are processed in).

I also disabled hardware graphics acceleration - to see if that might also be the cause.   SHe had 2 other issues (new emails came in and the window did not bump down the messages until she clicked and refreshed the window, and another time she opened the calendar in daily view and all meetings were 1 hour off from the numbers at the side, but clicking on the window refreshed and reset to normal.)  

Her OST is at 16GB and I've already warned her that, that is the next step.   Her inbox on exchange is over 7GB and she also has full access with automapping to 4 other inboxes that she manages.  My next step would be to disable the automapping on those extra mailboxes, and then created 4 exchange profiles in Outlook to break her OST up into 5 files (hers plus the 4 mailboxes) in order to reduce the size of the OST.   I realize this is not supported by Microsoft but it might be the better way.   I'm trying to determine what new issues that might cause and go with the lessor of the 2 evils.

I am currently waiting for her to reply back if/when the next issue occurs.

I have Outlook 365 tied to my hotmail account, running Win 7 with Microsoft Security Essentials with the only active addons running being the ones that came with the install.  I'm having a problem with emails that I accidentally deleted.  I found them in my "deleted items" folder, I moved them back to "Inbox", whereupon they disappeared after I reread them.  They are no longer to be found anywhere even after a restart of Outlook.  I had also been deleting other emails around this time.  The ones I wanted to keep never appeared (in blue) to be selected when I clicked the delete (X) yet maybe they were somehow?  I've tried to recreate the problem with some other random email from my deleted folder with no luck (it stayed undeleted even after I browsed away and back).  It is kind of irritating since those were sales receipts I was looking for.