The most likely reasons for this are that your Exchange inboxes:

• haven't finished synchronising yet (see the knowledgebase article "I've just been upgraded to Windows 10 and now Outlook isn't very stable.")
• have only recently finished synchronising and are still being indexed by the Windows Search service.

In either instance they should be fully searchable within a few hours. If you urgently need to search for a missing e-mail, use Outlook Web Access or the Southampton Virtual Environment until your computer has finished updating the Search index.

In some rare instances, this may also be caused by Cached Exchange Mode only having synchronised the last 12 months of your e-mails (the rest are still safe on the server). To check for this:

• Open Outlook and from File menu select Info
• Click the Account Settings drop down and select Account Settings

• On the E-mail tab highlight each affected account in turn, and click the Change button

• Ensure that Mail to keep offline is set to All. If this is not the case, and you are unable to change the slider, please contact ServiceLine for advice

• Click Next
• Click Finish