Ok, this is going to be a long story I suppose.
First of all I have to confess that I absolutely love MailStore Home. I am sure that I would have gone crazy without this tool! The only issue so far: the free version works perfectly well for me, which gives me a bad conscience since it is worth its weight in gold!
I started to distrust this tool because half of my "Sent items"-folder had the date 1/4/2005 after importing it into Windows Live Mail (my workflow for upload is now: use MailStore in order to convert the messages into .EML files which Windows Live Mail can import).
In Outlook (or OWA) they looked ok:
So, I was suspecting that MailStore somehow messed it up. So I spent the better part of an evening looking for a tool which would convert the .PST-file into .EML-files - to no avail or... well over my budget. Then I got the idea: since the only application I have around that can import .PST-files is... Outlook, why not import it again into Outlook - and the problem was present there as well. So, the problem is already present in the .PST-file already, even though Outlook displays the correct dates.
Well, I have no idea what the problem is... but I found that all these messages which got the date 1/4/2005 started with the lines
The correct date appears several times in the mail headers, so I just fired up the compiler and wrote a program which would simply delete these two lines - and voila, success:
Btw - meanwhile I managed to export my calendar as well... This wasn't too easy - as all attempts with Outlook or Windows Live Mail failed. But... it can't be easier. In Outlook one has to export it into ICS-format - and then simply upload it on the WindowsLive-calendar website, just hit the "Subscribe"-button. Can't be easier if one knows about it... I haven't bothered investigating what gets lost on this way - at first glance it looks good.