It isn't rocket science.

https://support.mozilla.org/en-US/kb/archived-messages http://kb.mozillazine.org/Archiving_your_e-mail

Thanks but i read it earlier and it's just a basic setup instruction. I interesting in more deep specs of this process, in collaboration with Win AD and unix networks, domain network.

It's not clear what form of "archivation" you are talking about. Christ1 has reasonably assumed the Archive option built into Thunderbird. If you mean something else, you'll need to be a little more explicit. ;-)

Thunderbird's Archive option writes the archives into the user's profile. I am not sure where networks come into this. It should write to wherever the profile is stored, beit local or on a network share.

It archives when I ask it to. The way it is done done depends on user settings; mine is configured to use years as the top level granularity, with subfolder tree structure honoured. The value of it is to break a large accumulation of messages into a significant number of small files, which better suits some filesystems than a small number of very large files. It is NOT an automated backup of user data.

I don't understand what algorithm you expect to discover. Which is why I ask what aspect of archiving you are asking about.

I'm sorry for my English. I'l try to explane my quastion. I'm interesting in he Archive option built into Thunderbird - thats wright. But i want to know what exactly thunderbird makes with letter when he puts them in archive? What difference between normal letter and archived letter? Which variations do we have (if we have)? Is there some difference in Win and Linux versions? How mail server can collaborate with it (if he can) ? Thanks for your help.

What difference between normal letter and archived letter? Nothing.

The Archive folder is like any other folder in the relevant Thunderbird Profile mail account. It is a storage for older emails, so releasing space in other folders. It has additional structure which can be set up under 'Archive Options' in that you can set it up to Archive by year, month and retain folder structure. This means you do not need to create the any folder names as it uses the name of the folder where the email was stored.

So if you clicked on the 'Sent' folder and selected/ highlighted all of last months 'Sent' emails and clicked on the Archive button, they would be moved from 'Sent' folder to: >Archives >>2014 >>>>2014-05 >>>>>>Sent

So you can still access and read those older emails in the usual way.

Why is it useful? You need to remember that emails which are kept on your computer are stored in mbox files. These are text files, each email is stored one after the other in the order they were downloaded into one file eg: Inbox; they are not stored as individual emails in individual files. It is more risky to keep all emails in one file; larger files use more memory; hence using other folders (as seen in the left folder pane) to organise emails. Archiving helps with organising older emails, so reducing the file size. It may help to improve performace.

The Archive option is not a backup - it is a means of organising older emails into smaller files that are still accessible via Thunderbird Folder Pane.