Personal folder files are unsupported over a LAN or over a WAN link
This article tells you why personal folder files (.pst files) are unsupported over a local area network (LAN) or wide area network (WAN) link. The .pst files are not meant to be a long-term, continuous-use method of storing messages in an enterprise environment.
The article also suggests two alternatives to .pst files. You can use .ost files or Microsoft Windows Terminal Services.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB297019.