Start *Windows'* safe mode with networking enabled - win8 http://windows.microsoft.com/en-US/windows-8/windows-startup-settings-including-safe-mode - win7 http://windows.microsoft.com/en-US/windows7/Start-your-computer-in-safe-mode

Still In Windows safe mode, start thunderbird in safe mode - http://support.mozillamessaging.com/en-US/kb/safe-mode

Does problem go away?

- If no, then problem is either: bug in Thunderbird, in your Thunderbird profile, your mail provider. Please post into topic the contents of Help | Troubleshooting | copy text to clipboard

- If yes, then still in Windows safe mode ... start Thunderbird normally

   -- If problem is still gone, then cause is a program loaded during windows startup.  Possibilities include: antivirus SW, virus/malware, background downloads such as program updates
   -- If problem is NOT gone, then cause is likely a Thunderbird addon - eliminate them by disabling each one at a time in Tools | addons | extensions and restarting

- If results are unclear ... possibilities include temporary conditions such as contention from other running programs, downloads related to windows update, ...

Please let us know your findings.

Thanks, Wayne. But, as I said, I've already tried ALL of recomendations which I've found on the net, including safe mode of Windows, safe mode of Thunderbird, stoping antivirus, turning off addons, etc... NO ONE helps. I tested Thunderbird with other mail providers and accounts from the same computers, and also tested the same mail provider from other computer (with other internet speed). In both cases without any problems.

As I mentioned, problem appears ONLY when downloading time for one message is more than 30-40 seconds. If downloading takes more than that time, Thunderbird can not complete (close) message, and doesn't make record in the popstate.dat file.

So, my question is: how I can extend that time? Maybe by makeing changes in Thunderbirds variables (config editor or directly editing)?

How big is your Inbox in Thunderbird? How big is your Inbox on yahoo?

And - what type of internet connection do you have? - is your computer connected via wireless?

Thank you very much, Wayne!

Here are my answers: "How big is your Inbox in Thunderbird?" - Around 1.8 GB. "How big is your Inbox on yahoo?" - The same, around 1.8 GB.

(I make Local folders, where keep archived messages, so in Inbox usually have messages for one year. Both in Thunderbird and Yahoo.)

"what type of internet connection do you have?" - ADSL, 10Mbps IN, and 1Mbps OUT. "is your computer connected via wireless?" - No.

For a pop account, 1.8GB Inbox on the server is *very* big and not likely to perform well.

Keeping your Inbox as storage area by using the pop option "Keep messages on server" is not great for a pop Inbox. You should should either:

• change to imap
• cut the size of Inbox on server, and turn off "Keep messages on server",

And in either case, make sure you have good backups of your Thunderbird data.

Thanks for replaying! I will try to reduce size of Inbox at Yahoo, but... why I didn't have a problems few years ago, when Inbox was 10 GB? Also, why this "very big 1.8 GB" doesn't bother Thunderbird on other computer, which have fast internet connection? Options with IMAP account or turning off "Keep messages on server" are not suitable for me. (Deleting messages from Yahoo, and then sending back to the "cloud" backup of the same messages is pointless job.)

> why I didn't have a problems few years ago, when Inbox was 10 GB

Unknown. But the Inbox in Thunderbird could not have possibly been 10GB - it doesn't support folders that big.

> Also, why this "very big 1.8 GB" doesn't bother Thunderbird on other computer, which have fast internet connection?

> Options with IMAP account or turning off "Keep messages on server" are not suitable for me. (Deleting messages from Yahoo, and then sending back to the "cloud" backup of the same messages is pointless job.)

Keeping them on the server is not a good backup strategy. And that option was never planned to be used with large message stores.

I have tried option with complete cleaning Inbox on server, leaving just 2 messages: one with large attachments, and one without attachment. I've turned off "Keep messages on server" in Thunderbird. Problem persist. After downloading large messages, Thunderbird stops. Then click on "Get messages", and second (light one) message was downloaded. Looks like solution, but it isn't. Because, even if I disregard the possibilities of keeping messages on server, I have to clik on "Get messages" several times to receive ALL messages in Thunderbird.

I agree with tou that keeping messages on the server is not a good backup strategy, but it gives me (beside second backup, first I make to the NAS) opportunity to access my mail far from home.

Wayne, thank you for the help anyway! Once more question: do you know which Thunderbird's variable I have to tweak in order to prolonge downloading time? I have already tried "mailnews.tcptimeout" (setting 600 seconds), without success.

re :1.8GB pop Inbox in Thunderbird.

For Pop mail accounts in Thunderbird, the Inbox is in Thunderbird Profile. Everytime it is trying to open a massive single file and write to it. No wonder it is struggling. (If you had a single msword or pdf document that was 1.8GB in size, it would use more memroy and take forever to open all pages.)

If that single file gets any corruption you are likely to lose the lot. So it is risky as well.

I would strongly advise you do something about that file. Inbox in Thunderbird looks like a folder in the Folder pane , but in reality it is a single mbox file.

Do some serious housework on that Inbox. Create some folders to organise mail. Move emails into those folders. Delete emails you not want. Note; any email you delete will become hidden and marked as deleted, so it is still using up space in that file.

Set up Archve Options and archive anything older than eg; 2 months. Archive options info: https://support.mozilla.org/en-US/kb/archived-messages

When Inbox is empty, compact it to remove all 'marked as deleted' emails. You don't usually need to empty the Inbox before compacting, but if there is any corruption, in your situation, you could lose a lot of emails.

Thank you, Toad-Hall!

I am aware of massive single "inbox" file, but as I know it can be problematic with files bigger than 2-3 GB. So, I organized my mails with a lot of Local folders, and keep "Inbox" files less than 3 GB. I doubt that this can be a problem, because with other computer (in the office, with fast internet connection) I have the same structure mail organization (i.e. the same "inbox" file 1.8 GB), and don't have any problems with Thunderbird.

Beside, yesterday I've tried not only to clean Inbox at Yahoo, but also Inbox at Thunderbird. It didn't help.

Todd-Hall, maybe you know which Thunderbird's variable is responsible for downloading time? I am sure that here is a key for solving problems. Because, I made some experiments with different size of attachments, paying attention to speed of my connection. So, one day I can download 2 MB attachment, but another day I have a problem with 1 MB attachment. But always I stuck with the same time - around 30-40 seconds.

Have you got any anti-virus/firewall software scanning incoming mail?

if yes, then stop scanning incoming mail. This will slow down incoming mail. It will still scan any attachments you open and Thunderbird does not auto allow showing of remote content.

there is also a means of increasing the timeout if this is causing an issue. Tools > Options > Advanced .> General Tab click on 'Config Editor' button it will tell you to be careful :)

In top search type: tcptimeout You need this line: mailnews.tcptimeout; Value =100 Right click on that line and select 'Modify' Change the entry to 200 click on OK

Close window - top right X click on OK to save and close Options.

Toad-Hall,

Reporter at https://support.mozilla.org/en-US/questions/1049726#answer-697818 by doing safe mode (if done correctly) will have already eliminated the possibility of AV or other software as causing this.

Of course this does not rule out hardware or server issues, nor Thunderbird itself.

As for settings, I had avoided addressing that question because it seemed useful to persue other possibilities first, and it seems to me that a setting change is unlikely help. But this is not an area where I have much knowledge. I'll loop in some people with pop expertise....

One further question - what is size of your popstate.dat file in your THunderbird profile, found in a Mail subdirectory at Help | Troubleshooting | Profile Folder | Show ??

Toad-Hall,

As Wayne kindly remind us, AV is eliminated. Regarding variable "mailnews.tcptimeout", I already said that it doesn't work (even 600 seconds).

Wayne,

I understand, thank you for help, anyway!

what is size of your popstate.dat for this account?

I will check later, but as far as I remember it's a small file - around 200-300 KB

Update: size of popstae.dat is 41 KB.

Wayne,

Maybe you didn't see, size of my popstate.dat is 41 KB.

Why is one computer on slow connection and one on fast? Exactly what are these connections and can you swap them to determine if the problem if the connection, or the computer?

And when it stops and you cannot get new messages, What happens if you do file, offline, work offline and then turn off work offline?

Toad hall please note your conclusion/info is incorrect when you say "For Pop mail accounts in Thunderbird, the Inbox is in Thunderbird Profile. Everytime it is trying to open a massive single file and write to it. No wonder it is struggling. (If you had a single msword or pdf document that was 1.8GB in size, it would use more memroy and take forever to open all pages.)

If that single file gets any corruption you are likely to lose the lot. So it is risky as well."

It is the folder _index_, the .msf file that has must be opened, kept in memory, and has the greater odds of having corruption. This file it far smaller than the file that is holding the actual messages. Therefore, at least for this user, there should be no struggle, as long as the folder successfully compacted after deleting/cleaning up the inbox.

Reporter, if you right+click folder and choose properties, what is the file size listed?

"Why is one computer on slow connection and one on fast? Exactly what are these connections and can you swap them to determine if the problem if the connection, or the computer?" Well, first is at home (slow), second is at the office (fast). Slow one: ADSL, declared 10Mbps download and 1Mbps upload (but with often interrupts), speed with Yahoo server is 1.6Mbps with Webmail, and 0.3-0.4Mbps with Thunderbird. Fast one: DSL, 20Mbps, speed with Yahoo server is about 5Mbps. I don't need to swap computer, I've already made experiment (for the slow connection, of course) with notebook: "clear" Windows 7, install ONLY latest Thunderbird and make new profile with ZERO messages, leave at Yahoo server ONLY 2 messages (one large with attachment, and one light with plain text). Thunderbird loaded just first (large) message and STOPS. After 10 minutes Thunderbird loaded the SAME first message and stops. And again, again...

"And when it stops and you cannot get new messages, What happens if you do file, offline, work offline and then turn off work offline?" I am not sure I understand you. When I have to go offline? Immediately after start Thunderbird?