there is telemetry data sent to Thunderbird servers to generate these statistics. https://stats.thunderbird.net/

So developers have some idea how the product is used. There is little point investing heavily in encryption if no one uses it for instance. There is also transmission of basic operating system and version information to determine if an update is available.

What does not occur is transmission of actual user data such as contact, addresses or mail contents. The official privacy statement goes into more detail https://www.mozilla.org/en-US/privacy/thunderbird/

Thanks for responding.

From your description, I would surmise that allowing Thunderbird to access Contacts does not in any way alter what data is transmitted from the user computer. Is this correct?

Thanks again for your time.

I think that is a pretty good surmise. I say that in the knowledge that at some future point the fact you allowed contacts may be included in telemetry. But not any of the actual contacts, or even the number of contact you have as that is not relevant to Thunderbird planning of features and enhancements.

The Thunderbird community is very conscious of privacy and really does not collect any data that can uniquely identify your installation, let alone the data that belongs to you. Hence the difficulties in estimating the number of active users of Thunderbird. It has always been, and will remain, little more than an educated guess because uniquely identifying installations is an invasion of the user privacy.

Matt, many thanks for taking the time to communicate with me.

FYI - I used Mac Mail forever but switched to Thunderbird recently, solely because of the way it deals with accounts configurations (it is very very good). The only niggle I might have with TBird is the way it deals with inline images although it's not definitive whether I may be overlooking something. I may at some point ask a question about it in this forum.

Sorry to hijack my own thread, but I'm curious if you actually work for Mozilla? In any case, thank you so much for taking the time to respond. I'm new here and this is only my second thread.

Cheers.

To bastardize a saying ;) "I work for a living."

Tractor driving, heavy machinery maintenance and livestock handling and anything else the day throws up on a few thousand acre grain and livestock enterprise.  ;) (you want something broken with a few hundred horse power there is a chance I am your guy).

I most certainly do not work for Mozilla. The most I ever got from them was a water bottle and a t-shirt. I just participate in the Thunderbird community as a volunteer and it is something of a hobby.

Thunderbird is not even a Mozilla project these days, they announced their withdrawal from new development in 2012. https://blog.lizardwrangler.com/2012/07/06/thunderbird-stability-and-community-innovation/ In the ensuing years Thunderbird almost died, limped along and in the past couple of years appears to be going from strength to strength. Long standing bug and enhancement that have in some cases lingered for a decade are now getting attention.

It is something of a development nightmare as the source code is built on the Mozilla platform and has resulted in some forced changes over the past few years. Often done in less that a satisfactory manner to meet code removals done by the Firefox folk, at time after the event when the developers found the program simply would not build. But I think the project is past those lean time and with community support will make some serious improvement in the next couple of years.

There exists a complex relationship between the Thunderbird community and the Mozilla foundation (The foundation does not make Firefox or any software as they are a US based charity that owns the corporation that makes Firefox.) To the point the folks employed using Thunderbird's community contributions work for a wholly owned Mozilla foundation subsidiary. But the whole is "managed" by a council elected annually by the community. Not by the foundation. (I said it is complex)

There are certainly some oddities with inline images, and these are exacerbated by Apple with their proprietary formats (sometime only subtly different from expected) and anti virus / security software that has a habit of blocking remote inline images. But ask away, I will answer you if I can.

I (and I'm sure many others) thank you for taking the time to help others.

Open-source software models and their associated communities fascinate me. I think the whole concept is hugely important and has massive global and political implications. The Mozilla story certainly seems to be quite complex (as you said).

Thanks for offering to entertain my inquiries regarding inline images. Later today or tomorrow I'm going to review my concerns and see how far I get. I will then start another thread with a specific question. I hope to hear from you then.

Pleasure talking to you. BTW - I'm a gear-head too, BMWs and muscle cars, serious hobby.