UITS recommends that you export certificates to removable media, such as a USB flash drive.

To export your certificate, follow the appropriate steps below.

When your connection to the Exchange computer is interrupted, you can continue to work with your data.

If you are using a Microsoft Exchange account, your items are usually delivered to and saved on the mail server.

To allow you to work with your messages even when you cannot connect to the mail server, a second type of data file that is named an Offline Outlook Data File (.ost) is kept on your computer.

Sometimes I can remove the mailbox and re-add it and it starts working but not always.

I have attempted to put Outlook 2013 in cached mode and without and still no change.

With Cached Exchange Mode, you do not have to set up Send/Receive groups, choose folders that you want to be available offline, and then keep those folders synchronized.

File locations: You can save, copy, and move a data file (other than the file that is used as your default delivery location) to another location on your computer or to a share on the network.

Also, for details about potential issues with various devices and applications when using digital signatures, be sure to refer to Known issues with digitally signed email at IU.

If you want to create a backup copy of your certificate or use it on another computer, you must first export the certificate.

About: There are two types of Outlook data files used by Outlook for Windows.

An Outlook Data File (.pst) is used for most accounts.

When you use Microsoft Outlook, your email messages, calendar events, tasks, and other items are saved on a mail server, on your computer, or both.