Sorry the image did not get uploaded - could you try again. It does sound unusual. 'Collected Addresses' is the default for collecting email addresses of people you send to, but only if they are not in another Address Book and if not then they should only be collected once. That's assuming there's no change in Display Name or if display name is the same no change in address. I have had one person collected twice before because they altered their email address. But your issue sounds a bit more drastic.

If you send an email to an email addess of a contact which is already in an address book eg: 'Personal Address Book', then it should not be adding that contact/email address to the 'Collected Addesses'.

Are those contacts/email addresses already in an other address book either 'Personal Address Book' or maybe another address book you created eg: Business, Friends etc?

If no, then try the following to see if this constant recreating of contacts and addresses can be controlled whilst trying to work out what is going on.

Create an Address Book and give it a suitable name. Select 'Collected Addresses' Move suitable contact(s) to the address book you created - (Left click on highlighted contact(s) and hold down to grab it then drag over to left side pane and hover over the desired address book and then release the mouse to drop contact into correct address book).

Please report back on results.

Also... What OS are you using? What version if Thunderbird are you using? What Language version of Thunderbird are you using?

I'll see if anyone has mentioned this as a bug report.

Just confirming.... You have not selected 'All Address Books' 'All Address Books' is not an address book, it is a virtual address book list of all contacts in all real address books including Personal Address Book, Collected Addresses and any other Address Book you created.

....because that will show a list of everything, so in this senario....if you have a contact in eg: 'Personal Address Book', 'Friends', 'Business' and 'Collected Addresses', ....then in 'All Address Books' that contact may appear 4 times.

I suppose a good image would help. Please upload image of Address Book showing you have selected 'Collected Addresses' then sort contacts by name and post image showing same identical name repeating with same identical email address. Thanks.

To switch off the collecting of email addresses you send - if desired ? Settings > Composition scroll down to 'Addressing' section uncheck 'Automatically add outgoing email addresses to my:' chosen address book which by default is Collected Addresses.

Thank you for your answer. Here's an updated screenshot. "zebrane adresy" is "collected addresses" in the Polish version of TB. I can't display the full names or email addresses, but as you can see, there are multiple copies of the same names. I know that I can uncheck the box "Automatically add outgoing email addresses to..." but it is quite practical to have this option "on". What I don't understand is why each email sent adds a new copy of the address to the "collected addresses book" TB 140.1.0esr / Polish / Win11 If the attachtment is not available, here is WeTransfer link: https://we.tl/t-3QP5GLsh9q

I can see there are multiple instances of name eg: 'Agniesz' Is there anything different for the email address or any other part of the contact details?

Does that person exist in any other address book?

re :I know that I can uncheck the box "Automatically add outgoing email addresses to..." but it is quite practical to have this option "on".

I agree.

re :What I don't understand is why each email sent adds a new copy of the address to the "collected addresses book"

It should not be adding another instance of contact unless there is something slightly different with the email address or whether you have added something slightly different to any 'display name' which is shown before the email address itself.

Thanks for image... You may not have have noticed when they were created. Do you notice if the duplicates are only created if you send one email to just the one person and then do the same again for another email? So end up with two entries. OR do duplicates appear if you are sending one email to more than one person eg: 2 or more recipients? I'm trying to find out if the duplicates appear because the email had a name that was added as Cc'd or Bcc'd. eg: an email to person X also had Cc to 'Agniesz'.

Have you installed any addon extensions? Where they are enabled or not... If yes, please offer the list - you can find this here:

• In Thunderbird
• Help > Troubleshooting Information
• scroll down to 'Add-ons' section
• Copy all the data and paste it into this support question.

Thank you for your time. 1. Is there anything different for the email address or any other part of the contact details?

No, there is no difference in adress of "agniesz..."

2. It should not be adding another instance of contact unless there is something slightly different with the email address or whether you have added something slightly different to any 'display name' which is shown before the email address itself

There is realy no difference. When I write an e-mail i often find recipient in my "sent" folder. I right-click and select the "edit as new" option. So this is exactly same person, same adress i write mail to.

3. "OR do duplicates appear if you are sending one email to more than one person eg: 2 or more recipients?"

I almost never sent email to more than one person at a time.

Installed add-ons Polish Spellchecker Dictionary dictionary 1.0.20160228.1webext true app-profile pl@dictionaries.addons.mozilla.org Allegro extension 1.0 true app-builtin allegro-pl@search.mozilla.org DuckDuckGo extension 1.0 true app-builtin ddg@search.mozilla.org Encyklopedia PWN extension 1.0 true app-builtin pwn-pl@search.mozilla.org Google extension 1.0 true app-builtin google@search.mozilla.org Quicktext extension 6.4 true app-profile {8845E3B3-E8FB-40E2-95E9-EC40294818C4} Wikipedia (pl) extension 1.0 true app-builtin wikipedia@search.mozilla.org Wolne Lektury extension 1.0 true app-builtin wolnelektury-pl@search.mozilla.org XNote++ extension 4.5.48 true app-profile xnote@froihofer.net Language: Polski (Polish) locale 140.1.20250718.22019 true app-profile langpack-pl@thunderbird.mozilla.org Motyw systemu — automatyczny theme 1.4.1 true app-builtin default-theme@mozilla.org Ciemny theme 1.3 false app-builtin thunderbird-compact-dark@mozilla.org Dark Fox theme 1.0 false app-profile {3e20e787-9cd4-47b3-8bff-b014f0dfa257} Jasny theme 1.3 false app-builtin thunderbird-compact-light@mozilla.org

re :When I write an e-mail i often find recipient in my "sent" folder. I right-click and select the "edit as new" option. So this is exactly same person, same adress i write mail to.

Thanks for info as I'm trying to locate if there is a bug when using a particular method.

Can you perform a few tests to try to nail down the bug? First I need you to access 'Collected Addresses' address book and remove all the duplicates (so only one instance remains) of a person who is willing to accept a few test emails eg: agniesz - it's important that whom ever you use is currently not in any other address - or if using a helpful friend who is in another address book - move that contact into 'Collected Addresses'. You can move them back after the tests.

Does the duplicate get added to Collected Addresses if you:

Test 1: click on '+New Message' and then start to type email address in 'To' field. A drop down should offer the contact email address so you can select it, saying you from typing all the address. Send a test email.

Test 2: click on '+New Message' and then use the 'Contacts Sidebar' Select the 'Collected Addresses' select contact name and click on 'Add to TO' button. Send a test email.

Test 3: REstart Thunderbird using 'Troubleshoot Mode'

• Help > Troubleshoot mode
• click on 'Restart'
• Click on 'Continue in Troubleshoot mode'
• In "sent" folder. Right-click on email and select the "edit as new"
• Send a test email.

Please report back on what you discover. Do any of the above tests reproduce the the duplicate in Collected Addresses?

thanks.