A while back some of my family switched their ISP from Qwest to Cox. I had recently sent an email directly to one family member and they had replied back that it went to their old ISP’s email at qwest.net. I was a bit baffled that the address was still active as it had been several months since they have switched. A bounce-back would very much welcomed here. Even more baffling though was I knew I had removed their old address and put their new address in my Thunderbird address book. I just went to send them another message and right as I was getting ready to click the send button I noticed the to address was their qwest.net address. I deleted what was in the To: field and started typing in their name. Both addresses showed in the drop-down.
After selecting the correct address and sending off the message, I went into my Thunderbird address book and confirmed I only had their cox.net address. However, I noticed in the left column another ‘address box’ called Collected Addresses. I looked through this address box and there was their qwest.net address.
I sorta knew what the Collected Addresses were but wanted to find out more. A Google search on the topic turned up a lot of information, but not so much from Mozilla. I did find a good description at the Cornell University site:
Collected Addresses is a special address book that Thunderbird maintains without any effort on your part. It is made up of every e-mail address to which you’ve sent a message, whether in To, Cc, or Bcc. (You can control how Collected Addresses works through an option setting.)
As installed, Collected Addresses is a convenience in that, once you’ve typed in an address, you’ll never have to type in that address again. As you start to type it, Thunderbird will find it for you.
More searching (again not much from Mozilla without having to really dig deep into their discussion forums) I found The Unofficial How-To Blog for Thunderbird. You can disable the automatic addition of ‘collected addresses’. From Thunderbird go to Tools > Options… (Mac: Thunderbird > Preferences | Linux: Edit > Preferences) and click on the Composition tab. At the bottom is an option to Automatically add outgoing e-mail addresses, uncheck this option.
So now I have removed their old address from Thunderbird completely and also stopped having Thunderbird collect addresses. Quick tip, in Thunderbird 3.0 and newer clicking the star next to the sender’s name will allow you to add them to your address book.