ODIR is an add-on for Outlook that can detect duplicate items and move them to a special folder; these include contacts, appointements, tasks, notes, and emails (sent, received, and unsent). Does not work with Outlook Express.

I used this program with Outlook 2007 to scan around 18,000 emails for duplicates.

Of these, approximately 10,000 were duplicates (after migrating my email from Thunderbird to Outlook, I somehow created 2 copies of 5,000 of my emails).

Here are some notes on my experience with this program:

  • Running the program: the installer creates an ODIR menu alongside Outlook’s original menus. Deduping begins when you select ’Remove Duplicate Items’ from this menu.
  • How it works: items are considered duplicates if the following criteria are found duplicated: for contacts: first and last names, company name, and email address; for appointments: subject, location, start date, and end date; for tasks: subject, start date, due date and status; for notes: contents of the body and color; for emails/posts: internet message ID (for received email), email subject and the time sent (for sent email), and the subject alone for unsent emails.
  • Effectiveness: it took about 4 hours for ODIR to sift through 18,000 emails. It was a processor-intensive affair and at times I found myself wishing that there was a pause button or even a mere indication that it was still chugging along and not crashed (the progress gauge was moving very slowly). No sooner than it was done, after about 4 hours, that it crashed. Fortunately it had already moved all duplicate emails into the ODIR_duplicate_items subfolder, and I was able to delete those. I speculated as to whether the crash was due to an incompatibility issue with Outlook 2007. In any case, the job was done.

I searched for a very long time for a free program that can detect duplicate emails in Outlook and I am very grateful that I found this one. In the end it did a very fine job.

Version tested: 1.2.1

Compatibility: A Windows machine that runs Outlook. Does not work with Outlook Express.

Go to the program page to get the latest version (approx 1.87 megs).