From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0RC1+) Gecko/2002051607 [wrong, haven't modified Evang cookie yet] BuildID: 2002051907 I decided to clean up my Collected Addresses book a little, to delete spam addresses I now had filters in place for. While removing these, I noticed that a lot of addresses were in there several times. In once case almost a dozen entries. Some of these were due to different case in name and e-mail address, others, I couldn't see any difference in the syntax (my Target E-statement, for example, appeared identically 4 times) I see this as a problem since collected addresses is usually limited to a specific number, and this causes that number to be reached too quickly, and there are probably performance probs as well. Plus, it offends my redundancy sense. I think collected addresses should be checked for uniqueness in e-mail field, case insensitive. Blu3 says the RFCs allow case sensitive e-mail addresses, but I could not find that in perusing the various mail RFCs, and Sendmail delivered a series of test messages to me, no matter what I made the case. Reproducible: Always Steps to Reproduce: 1. Open Address Book, Collected Addresses 2. Scroll down until you see similar looking entries

There was a bug which was fixed recently. Probably, you are seeing those. Do you still see new dupes in the address book? pi

How recently? To test what you said, I sent in the above build, mail from: foo@bar.com FOO@bar.com foo@BaR.com I ended up with 2 entries in my Collected Addresses. One for foo@bar.com, the other for foo@BaR.com

What you are seeing is bug 129393. pi *** This bug has been marked as a duplicate of 129393 ***

Verified Duplicate.

To the best of my knowledge this bug still exists in the main code. To get it fixed please go to bug 129393 https://bugzilla.mozilla.org/show_bug.cgi?id=129393 and click the vote button to raise its level of importance.