Slight Size Difference in Contacts when Moved from PAB to Public Folders

Slowhand

So this is something's that come up as a head-scratcher in both my 70-662 studies and, today, at work.

When I move my Outlook contacts from a Personal Address Book to Contacts on Exchange, I'm seeing a slight difference in file-size of individual contacts, (and in .msg files when I pull them out of Outlook to compare as stand-alone files). When I open the contact card in Outlook (2010) and go to the File menu, the properties field will show a difference of a few kilobytes between the local contact and the one stored on Exchange, (in this case, they've got their address books set up in Shared Folders.)

What I'm not seeing is a difference between the fields, none of the actual data seems to be missing, (there are hundreds of contacts, so I'm taking a sampling of about 25 random contacts to compare.) I've tried copy-pasting the contacts from local to public, as well as doing an export of a .pst and importing it into the public address book, and I'm seeing the same result.

This isn't something that I'm particularly stressed about, but my client's had a pretty rough time getting all their mail settings moved from the old Exchange box to the hosted Exchange solution so there's a bit of extra worry coming from them. In order to put my client's mind at ease, I just want to get confirmation that this is nothing to worry about so long as all the actual contact data is intact.