What bloated my Outlook.pst file?

[MS]

Strange story, but true.

My Outlook.pst file was getting rather large, over 47 MB, so I decided to do
some cleaning. I deleted many unnecessary e-mails (a large portion of my
Inbox) , then deleted them from the "Deleted Items" folder.

I was surprised, however, to look in my Outlook data folder after that, and
saw that the size of the file had increased to over 97 MB, more than double!
(I could understand it not decreasing yet, as I hadn't compacted it yet, but
didn't understand the increase!)

I then compacted it. That shrank it to over 87MB, less than the 97MB+, but
still much higher than the 47MB+ it was before the deletions and compacting.
I ran the scanpst program on it, it showed no errors. I could not figure out
what caused this.

Finally I did a workaround. I started a new PST file, and I copied all the
data from the bloated one to the new one. The new one, with all the same
data as the 97+ and 87+MB files, is 33+MB in size.

I'm still curious about it though. What could have caused the size of the
file to increase to more than twice its size, after deleting a lot of
e-mails and compacting the file?

 

[Vince Averello [MVP-Outlook]]

You might have to compact more than once to get all the space back. I've
seen it take 2-3 cycles to get things right.

 

[MS]

You might have to compact more than once to get all the space back. I've
seen it take 2-3 cycles to get things right.

Tried it. Didn't work. The problem doesn't seem to be just one of
compacting. Why did the .PST file double in size when mail was deleted?
Deleting without compacting will not reduce the file size, but it shouldn't
double it. Obviously something strange went on.