User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727) Build Identifier: 20080213 In the options we can tell TBird to add addresses to the "Collected Addresses" addressbook as we send out eMail. We can point that at our normal Addressbook also. If the eMail address already exists within the addressbook it is not supposed to add it a second time. Often the user will type the eMail address in as "Proper" case. If it is already in the addressbook as "Someone@SomeWhere.com" and the letter going out is addressed in all lower "someone@somewhere.com" even though it is the same it adds it a second time or each time for each case difference. Could we make that feature so that it is NOT case sensitive please? Reproducible: Always Steps to Reproduce: 1.Add "Someone@somewhere.com" to your address book or where the addresses are collected to. 2.Send a letter to "someone@somewhere.com" (Note all lower case) 3.Go look and see the duplicate in that addressbook. Actual Results: Same address in the address book many times. Expected Results: Seen that the address was already there just in a different letter case and not added it again.