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How to compare the MAPI property differences between Outlook emails

I was recently working on extracting mail from Outlook to an .msg file and later importing the .msg file back into Outlook. I was concerned that some of the non-obvious properties (there are a lot of non-visible MAPI properties stored on an email) would not be persisted or may change value in the process of the export/import. I thought this was going to be a daunting and time consuming process comparing the value of around 100 MAPI properties and playing spot the difference. Luckily the first thing I tried was the awesome OutlookSpy tool which I’ve found simply brilliant for assisting with Outlook development over the years. What I didn’t realise was that OutlookSpy has a build-in compare feature that will compare the MAPI properties of 2 mail items and highlight:

  • Properties missing/extra on the 2 objects being compared
  • Properties with different values on the on the 2 objects being compared
  • Properties with the same values on the on the 2 objects being compared

 

Steps compare the properties on 2 email messages using OutlookSpy

 

Select one of the emails to compare and select OutlookSpy | IMessage

cameron-dwyer-outlookspy-compare-01-IMessage

 

The IMessage window will appear showing all the MAPI properties on the item. From here select the Compare tab.

cameron-dwyer-outlookspy-compare-02-IMessageWindow

 

In order to compare this email against another email, the compare tab gives you a green area where you can drag and drop the PR_ENTRYID property from a different email message. So to do this leave the IMEssage window open on the compare tab.

cameron-dwyer-outlookspy-compare-03-CompareTab

 

Go and select the email you want to compare to in Outlook and select the OutlookSpy | IMessage button for this new email. You will be presented with the IMessage window and shown the MAPI properties for the new email. Locate the PR_ENTRYID MAPI property in the table (hint: click the column header to sort the table). Now drag and drop the PR_ENTRYID row from the table into the green drag/drop zone on the original IMessage window that you left open.

cameron-dwyer-outlookspy-compare-04-dragdrop-pr-entryid

 

Now the magic happens! The compare tab does a comparison of the 2 items and allows you to switch between properties with the same values, properties with different values, and missing or extra properties.

cameron-dwyer-outlookspy-compare-05-properties-same-on-both-email

 

cameron-dwyer-outlookspy-compare-06-properties-different-on-email

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