User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:34.0) Gecko/20100101 Firefox/34.0 Build ID: 20141127111021 Steps to reproduce: 1. On a Ubuntu 14.04 PC 2. Thunderbird address book has several Smith email addresses 3. Compose email to John Doe <jdoe@yahoo.com> 4. Entered 'To' address of recipent starting with jdoe and the remainder autocompletes 5. on next line, entered 'cc' address by typing in 'Smith' and selecting 'jSmith@msn.com' from pic-list of several 'Smiths' 6. On pressing enter, a blank 'cc' line appears with 'asmith@gmail.com' on the 'cc' line above it ..asmith@gmail.com being the first Smith on the pic list Actual results: On entering part of an email address, to select from a pic list of possible email addresses, followed by 'Enter', the email address that is retained on a destination line ends up being the first email address in the pic list of possible email addresses; not the email address chosen. This makes it all too easy to misdirect an email copy. Expected results: On entering part of an email address, to select from a pic list of possible email addresses, the email address that is retained on a destination line, after pressing 'Enter' should be the chosen email address