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BCC'd emails addresses are revealed! Whose fault is it?

by Lee Koo (ADMIN) CNET staff/forum admin / September 9, 2016 5:18 PM PDT

I have some serious problems with Hotmail / Live mail accounts and I hope you can help. I flawlessly switched from Windows 7 Pro to Windows 10 Pro with a few glitches that really haven't been an issue. (e.g. I cannot get my Cortana to recognize I'm connected to the net which is how I discovered this new problem, because I only liked Thunderbird anyway.)

I have used Firefox and Thunderbird email applications from the beginning and I like their platform very much, but I recently sent a message to all of my friends using BCC (which is the ONLY way I email multiple individuals) -- however, the entire message was sent regularly, NOT BCC even though my sent file shows it as being sent BCC. One of my friends thanked me for sending him all of my contacts??!!??

I've been reading online that a lot of others have had this problem and there is a controversy as to which is at fault, Hotmail or Thunderbird. Since Microsoft Hotmail is involved I automatically blame them. Over the years I have been well trained by them to know they are wrong 99% of the time.

Regardless, anyone using Hotmail/Live mail with Thunderbird may be in jeopardy of having all of their group addresses revealed to others.

Of course, this doesn't resolve the problem. So what to do now? Have others using Thunderbird in conjunction with Hotmail experienced this? I've started using another email for better security until this is fixed.

I would like to hear your take on this please. Thanks for your time!

--Submitted by PT B.

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Some random thoughts
by Zouch / September 9, 2016 11:55 PM PDT

I can't really answer your specific question because I don't use either Windows 10 or Hotmail/Live Mail but I have used Thunderbird on XP and Win7 since it (Tbird) was in the 0. betas.

The commonality I have with you, though, is that all my mail servers, my primary one I won't name, one that came with my mobile phone from Virgin Media and a Google "throwaway" gmail account, all use webmail servers as their platform, each with a lousy interface. So I use Thunderbird (separate account inbox option) to access all three.

When I set it up, there was the option to use IMAP (messages stay on the server) or POP3 (messages download to my PC) and since I'm not always online, I opted for POP3, with automatic deletion from the server when I download. In this configuration, all my replies and new mail goes through an SMTP server at my ISP (none of the above - it does make sense, honest!). While I've not seen your problem, if I did, it would be highly unlikely that Microsoft would be to blame because, a newly composed mail would only run through Thunderbird and my ISP, not through any of the inbound mail servers.

This would not be the case, had I opted for IMAP with the messages on the inbound mailserver, so that might be an issue in your case.

When you said you were using another email, did you mean other than Hotmail or other than Thunderbird?

If your problem is consistent, I'd be inclined to try a different email client (there are lots on the web) to your Hotmail account. If the problem goes away, it suggests Thunderbird might be the culprit, though I think unlikely. If it doesn't, try using the Hotmail send/reply mechanism (I assume it has one) and see if that cures it - if so, it suggests a mismatch between Hotmail IMAP/POP3 and Thunderbird. If you are using Thunderbird IMAP to Hotmail, you could try POP3 (but set it not to clear the messages from the server in case you want to go back). If you try this, you will need to set up an SMTP server for your outbound messages.

If you problem isn't consistently repeatable, that's a whole new bag of worms and much harder to investigate. The above generalities might help but it would take a time to confirm.

Good luck!

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SMTP required with IMAP and POP3
by applegaa / September 16, 2016 6:06 PM PDT
In reply to: Some random thoughts

IMAP and POP3 are just methods of accessing your inbound messages. Sending messages still requires an SMTP server no matter which you use.

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Hard problem to nail down...
by Lee Koo (ADMIN) CNET staff/forum admin / September 16, 2016 2:23 PM PDT

Doing some internet searches on this topic, a couple of people mentioned that on some email clients, if you leave the "To" field blank, it will automatically populate the "To" field the email addresses in the BCC field (stupid system if you ask me.) Not sure if this is the case for you, but you may want to test out this theory on your Hotmail and Thunderbird setup.

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Tbird add on.
by jefferygale / September 16, 2016 7:45 PM PDT

G'day, thought I might tell you about the Tbird add on I use called Mail merge 4.6.1 by A Bergmann that if set will only send as BCC. Jeff.

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Fails for me too
by jjmartin1340 / September 16, 2016 7:57 PM PDT

I have a PC with Win7, I use Thunderbird and Gmail. I download all mesages into Thunderbird, don't look at them on Gmail. I just tried sending an email with nothing in the To field, and 2 addresses under Bcc, mine and my daughter's. When I received the mail addressed to myself, the message header bar (From, Subject, To, Bcc) had my addess in From (as it should), nothing in To (correct), but in the Bcc area it had BOTH addresses. I called my daughter, she is using an Apple computer and checks her mail on Gmail using her browser. When she looked at her message, it said "undisclosed recipients", no addresses. This is how it should be. BUT, it appears that Gmail is including ALL the Bcc addresses in each message. I always assumed that when I sent a message with Bcc addresses, Gmail would duplicate the message for each address, but remove all the other addresses from each one. It appears this is not the case. It looks like when Gmail receives a message with multiple addresses under Bcc, it does not display them itself, but if the message is downloaded, the multiple addresses are sent in the message. I don't know if other email systems also send multiple Bcc message that include all the Bcc addresses, or if this is just a Gmail fault. I don't know if there is a standard for Bcc in email, but I would expect the SENDER to strip off all Bcc addresses except the one ihe message is going to. Clearly Gmail is not doing this.
Conclusion: if you send a message by Gmail to multiple Bcc addresses, every recipient can see ALL the Bcc addresses if they are using Thunderbird. Not known if other email providers do this.

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more on this
by jjmartin1340 / September 16, 2016 8:18 PM PDT
In reply to: Fails for me too

I just had my daughter send me a message to me with other addresses as Bcc. I did NOT see any Bcc addresses. So I had her send one with all addresses, including mine, as Bcc. I did NOT see any Bcc addresses. So -- does Gmail only include all Bcc addresses when one of them is also the sender? This is getting weird.

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It looks like Thunderbird ...
by Villano / September 18, 2016 9:16 AM PDT
In reply to: more on this

Friends, I have used Gmail, Yahoo and, besides corporate email servers. I have done so while running Windows XP, WIndows 7 and Windows 10. I have never experienced this problem, not have I ever known of such.
I would stick by statistics: if the culprit was Gmail, we would have thousands of cases (at the very least). So, I discard Gmail.
Second, your daughter uses Gmail but not Thunderbird and she does not see any BCC nor do you when she sends the mail. WHats is the difference? She uses just Gmail, you use Gmail AND Thunderbird.
I would also discard Windows 10 as the culprit, also for statistical reasons. With millions of users, we would have thousands of cases (and complaints!).
Even though I have some private reservations regarding hotmail, I would not blame it either. My experience with mail "collectors" has not been satisfactory. I have had problems with the mail application on W10, with the mail apllication by Apple (iPad and iPhone). The onlu one that has not failed me has been Outlook.

I would recommend our friend PT B to try using Hotmail diectly from Internet and discard Thunderbird. I( am sure the problem will dissapear.

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BCC Exposure
by Patndianne / September 16, 2016 8:16 PM PDT

I had a similar problem with eClient mail services where all names listed in the BCC addressee line became visible to all. I also have Thunderbird and the same thing happened with it. Both email services are MS Hotmail based so after reading last week's preview from PT for this week's discussion I assumed it was an MS problem. There have been changes within MS Live, Hotmail, Outlook and other areas of the MS family of email services this summer and wondered whether something in the changes triggered a glitch in MS email services to cause the problem. I have not checked my Gmail for the error and although the error occurred more than once it has not been an issue in the past few days. All of my emails are interconnected meaning I use the same extension, i.e., I have been using all three mail services this way for a few years and the problem only cropped up about two weeks ago and occurred on three different occasions.

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Many problems with MSN and Hotmail Accts with Recent Changes
by akt1000 / September 16, 2016 8:25 PM PDT

My recent problem with BCC email addresses with MSN and Hotmail accounts (using Windows Live Mail 2012 and IMAP and SMTP servers) is similar, but exactly opposite of yours: the emails are never sent to the BCC addresses. This is probably the result of the changes by Microsoft over the last couple of months in outlook. com accounts through which MSN and Hotmail accounts are being processed. (the changes also created some other unresolved issues, but that is another story).

I put a question on the BCC issue on the Microsoft Community forum also, but unfortunately did not get any response.

In my case, the BCC problem is only with the MSN and Hotmail accounts: everything works fine with my gmail account (using Windows Live Mail)

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Follow up on recent changes...
by cbcuono / September 21, 2016 10:22 AM PDT

Users of eM Client are experiencing the same issues with MSN/Hotmail accounts, namely, when addresses are added to the "bcc" field in eM Client, they are never sent. One can easily check this by opening the web-based Outlook, and you can see the distribution for the email, and the bcc field will be empty. If you send the email directly from the web application, then you will be successful, and you can confirm there. Contributors to the eM Client Forum have opined that Microsoft has, in recent months, altered its API processing, and therein lies the culprit.
For more info, you can read the eM Client thread:
and also the thread on MS Community:

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It is partly CNET fault!
by archibaldpaul / September 16, 2016 9:39 PM PDT

You did not get responses. That just might be because you are password-protected, and I have at least 36 passwords to take care of, and yours is not that important, so I never know it when I try to reply. This time, however, what I have to say is important, and I took the time to figure out what password I chose for you, possibly more than 5 years ago, and never used.

I have been a Hotmail user for a long time, before 2000. I send and receive a lot of e-mails. I have a regular list of friends I forward cartoons to, that I do not want revealed, and so, always use "BCC" for them.

NO MATTER -- Hotmail does not know what a BCC is, and certainly does not process them correctly, any time, every time, for at least the last 8 years. I thought everybody knows that! I simply have waited, revision after revision, for them to fix it, but they never have. Surely they know it does not work! I remember when Mr. Koo started his job as a single man; I do not think it even worked then. You can publish my name: it is Paul Archibald, everyone else has and it does not hurt my privacy.

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Hotmail & CNET
by Villano / September 18, 2016 9:23 AM PDT

Dear Paul, I tend to agree with you in thinking that hotmail has some part of the guilt. I still believe the main culprit is Thunderbird, buy for many reasons I don't trust hotmail.
At any rate, don´t blame CNET. We are in a password protected world where everyone requires a password to enter anything, and it mostly serves to free the site administrator's conscience in case anywyhing happens. I would recommend you to create an algorithm to build your passwords so you can "rebuild" it in case you forget it. Or to keep a copy in plain old paper, stuck somewhere with your passport and other documents.

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BCC's emails addresses are revealed! Whose fault is it?
by 5htej23 / September 17, 2016 1:02 AM PDT

I have been using a TBird add-on called "Use BCC instead" which allows you to set a threshold to determine when to convert all addresses to BCCs. In my case, I set it to two so that it will always convert addresses to BCC unless there is only one.

My mail is handled by a private server (PowWeb) ,,,,,sshhhhh, don't tell Hillary.....

I tested it so long ago, and didn't see a problem such as this, and haven't heard any complaints.

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Still using BCCs!
by JazNorton / September 17, 2016 2:08 AM PDT

I treat all emails received where I am a BCC with extreme suspicion. Almost all of them are at the best spam and at the worse contain some sort of malware. I would now never use a BCC list to send out emails to friends or colleagues, etc. It is so easy (and free) to set up a proper distribution list where everybody receives their own personalised copy of the email. I am amazed that any are still using BCC lists for such distributions.

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There are reasons for using BCC
by carlos_spork / September 17, 2016 7:23 AM PDT
In reply to: Still using BCCs!

The reasons you provided are certainly valid but, under certain circumstances many of us are legally required to use BCC, mainly for business-related emails.

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Linux servers un-BCC
by OSUnTexas / September 17, 2016 6:01 AM PDT

Years ago, I friend that runs a software company told me she was able to un-BCC mailing lists because she used Outlook run a Linux server.

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BCCs revealed
by billsailer / September 17, 2016 6:54 AM PDT

I have verizon, and when I send out a gang email no addressee is shown in the sent mail on your list of sent emails. If I open it, under bcc is the list of all the names that I sent it to. This includes forwards and original emails. All the addresses are shown in the sources when I open that. I always believed the bcc worked until today, now I am wondering too.

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My two cents
by carlos_spork / September 17, 2016 7:10 AM PDT

First things first: I'm very impressed and humbled by the many thoughtful and thorough answers posted by other members in regards to the issue you reported.

If I go past the healthy but unrelated venting I've read in those posts, I can only agree with the other community members when they point out how hard it would be to pinpoint the exact source of the problem, mainly because of the countless and complex variables at stake here (i.e., the email server setup for your specific hotmail account and the setup of your email client).

My advice, for what it's worth, is that you start writing down a detailed troubleshooting plan based on a matrix involving all the possible points of failure you can think of (if needed, ask a friend with troubleshooting skills to help you with it). And, what's more important, stick to the plan.

Now, having said that, you'd probably need to know that I'm using Hotmail as my only personal email account since 1997 and I've tried most of the popular and not so popular clients. I send emails with BCC'd addresses on a daily basis (from my personal Hotmail and my Office 365 accounts), and the only time I experienced exactly the same issue you had with BCC'd email addresses was when I tried to use my Hotmail account on Thunderbird with a POP3 setup. And it happened only once because I stopped using Thunderbird at once, mainly because I had never experienced this issue before using other email clients. I'm using Microsoft's Outlook client for over 10 years now, and I've never had this issue ever since.

I sincerely hope you can resolve your issue, because its pretty unsettling not knowing when it's going to happen again.


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bccs revealed
by billsailer / September 17, 2016 8:01 AM PDT

called Verizon, and they told me since the email sent to people as bccs are supposed to get the message, they also will always get the full list of bccs. That is unsatisfactory to me, but aside from writing to Verizon, I do not know what other action we can take. If I get a problem and someone asks me to help, and I send out an email, and bcc them. they should be allowed to be anonymous. They wanted me to try to correct a problem, and the person who is being corrected should not know the original complainant if that is what I choose.

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Re: bccs revealed
by sidel1932 / September 17, 2016 9:57 AM PDT
In reply to: bccs revealed

I just did a series of tests using my gmail address and two verizon addresses.
In each case, the BCC recipients received only the sender's address, their own email addresses and the primary recipient's address - not the address of the other BCC recipient.

If the primary recipient was the sender, he received all the recipient addresses, including the BCC addresses. But when the Primary Recipient was not the sender, he received only his own address and the sender's address; no bcc addresses.

This does not match your phone report from verizon that bcc recipients will get the full list of BCCs.

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by netsiu / September 18, 2016 8:37 AM PDT
In reply to: bccs revealed

If you are emailing back and forth with a single person, why are you ganging it with others? makes no since to me.

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Same M O
by fhl7849 / September 18, 2016 4:39 AM PDT

Hi, had the very same problem myself........I'm an experienced computer buff and could not trace the root of the problem. Solved it by throwing out Thunderdird and going back to my old email client "Incredimail" with which I've never had this trouble. To be honest....didn't really like Thunderbird anyway so no loss!

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Reson for not posting
by netsiu / September 18, 2016 8:30 AM PDT

I use Outlook 2007 and have mabell accounts. I have never had a reason to hide send to emails so have never tried to find a way so until this post by pt b never knew what bccd was, so never posted on something I never use or knew about.
Probably why so many others never did either.

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