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I need to compare an email list with a list curated by someone else and see the % of overlap.

The first thought is to make hashes out of each email. However this only works until a match is found. Once we have overlap we will both know who is a double-subscriber, and this is arguably confidential info.

Any idea how to do this.

Is there any service that would allow us to compare? I am thinking that the matches would be meaningless for that 3rd party.

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Tina
2011-07-10 22:32:00
Andy,did Joseph's solution work for you? Please let us know!
Joseph Gorman
2011-07-04 04:14:00
If the lists are in excel format (or can be opened in excel), here's a quick way (2007+). First, select both lists. Second, go to Conditional Formatting -> Highlight Cells Rules -> Duplicate Values. You can select the cells based on their formatting in the full find/replace dialog if you want to or just look at the cells.Source: http://chandoo.org/wp/2010/07/01/compare-lists-excel-tip/ (also contains a method to do this in excel 03).