What you say is not normal behavior for Thunderbird.

Are you using IMAP or POP? Have you logged into the webmail to confirm exactly what is on the server?

Please post here the Troubleshooting Information from Thunderbird: Thunderbird menu: Help: Troubleshooting Information Click the "Copy text to clipboard" button. Paste the text into your response here.

Thanks for the reply. Please be patient I need your help. Here is some background info. Windows user starting with Win2000. Currently have three Win 7 Ultimate systems. I will not ever have 8, 8.1, or Windows 10. I am transitioning to Linux. I've used Outlook Express, Windows Mail, Windows Live Mail, and Outlook. All set up with POP3. I've had the same ISP for over 20 years. My main computer is a laptop with 2 hard-drives. On one HD is Win7 Ultimate. On the second HD is two different Linux systems. Now that I'm using Linux I need an e-mail client that will work on everything. Thunderbird has been great so far but it is inconsistently downloading e-mail. In all of my earlier e-mail clients I could choose to “Leave messages on the server” and this allowed me to check mail on several systems and have the same on all of them. Occasionally having to clean up the server free up some space. This worked flawlessly until Thunderbird which has the same setting but seems to have no affect on what I get in my various Inboxes. Here are some examples of the problems I’m having with Thunderbird and POP3: 1. E-mail account #1 has three e-mails in the Inbox and a fourth arrives. I close the program and re-boot into a different OS and check e-mail. The same account has the same three e-mail but Thunderbird won’t download the new e-mail. Manually checking doesn’t help. I then log into my ISP account and look at the Web-mail for that account and find all four e-mail are sitting there. This is one of the inconsistencies I’ve run into. 2. E-mail account #2 has 100 e-mails in the Inbox and gets 10 more. I close the program and re-boot into a different OS. This time I check my ISP and find all 110 e-mail are there. I log out of my ISP and check e-mail and with the same “account #2” settings Thunderbird downloads the 10 new e-mail so the accounts are in sync in both OS’s except for one thing. When I log in to my ISP again and check the server, I find that the original 100 e-mail are still there but the 10 new ones are now gone. So when I try to check this account on another computer I can only get the 100 e-mail. The “Leave message on server” setting is the same on ALL of my accounts. Why does Thunderbird arbitrarily not honor that setting? 3. E-mail account #3 is newly set up on a computer and all account settings are the same as on two other computers. Both of the computers Inboxes are in sync with 200 e-mails in both and the same 200 are on the server. I get the new account set up and check the mail and nothing downloads. I send a test message which works and downloads as expected but the 200 existing e-mails won’t download from the server. These are three examples and I have a couple more that I haven’t had time to troubleshoot. I have been promoting Thunderbird and really like it. I think these problems are new but don’t have previous version info. I have all five of my systems automatically update Thunderbird, but I now think this was a mistake and now all of e-mail is a mess. Someone suggested using Imap, and I have been testing it, but why should I have to convert everything to Imap when POP3 has worked perfectly for over 20 years. The only reason that it’s broken is because of Thunderbird. I’m going to install Outlook on all of my Windows systems with POP3 and see how it goes. I really want Thunderbird to work.

Thanks JB

OK, why are you not using IMAP? It seems to me to be the obvious solution in a situation where multiple computers are looking at one server. POP wasn't designed for this, and setting it to leave messages on the server is a clumsy kludge.

Please post the Troubleshooting Information, as Bruce asked you. We are missing some useful clues about the mail provider.

Are you sharing or transferring a profile between computers?

I want a completely downloaded copy of my e-mail on every computer. This has worked perfectly for years! Why should I change? I don't understand why everyone wants to avoid the issues. I have been testing Imap and it sucks compared to POP3___I need a downloaded copy of all e-mail. POP3 used to work and I had exactly what I needed. This is a Thunderbird problem and I won't change to Imap to suit Thunderbird's bugs. I'm trying to be patient but I keep hearing the same thing. Using Imap is not an option.

Please post the Troubleshooting Information, as Bruce asked you. We are missing some useful clues about the mail provider.

Are you sharing or transferring a profile between computers?

I have seen so many users dismayed by POP. They try it and it sucks their precious collection of email off the server and they wail, asking how to put it all back. It's hard to find that window of opportunity to install the account and adjust it to leave on server before it runs for real and wrecks your stash. A few servers apparently ignore "delete" instructions and so this doesn't happen. And these are quirky little idiosyncrasies that can't be relied upon since they are not standard POP behaviour. And then other POP users get occasional glitches where everything they have downloaded previously arrives again.

If you'd been trying to help others as long as I have, you'd understand my reluctance to engage with forcing this square peg into a round hole.

POP has to track which messages have already been downloaded to a particular client. In Thunderbird this is done using a popstate.dat file. If you are moving a profile about between computers (another question you haven't condescended to answer) then it will bring this history with it. Or maybe you did answer it, but your solid wall of text is discouragingly hard to read and parse.

No I don't move profiles. I also submitted the troubleshooting" info. to another mozilla guru and his answer was "have you tried using Imap"

  Name: Thunderbird
  Version: 45.5.1
  User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1
  Profile Directory: Open Directory

            (Local drive)
  Application Build ID: 20161130104158
  Enabled Plugins: about:plugins
  Build Configuration: about:buildconfig
  Memory Use: about:memory

Mail and News Accounts
  account1:
    INCOMING: account1, , (pop3) pop.cox.net:995, SSL, passwordCleartext
    OUTGOING: , smtp.cox.net:465, SSL, passwordCleartext, true

  account2:
    INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

  account3:
    INCOMING: account3, , (pop3) pop.cox.net:995, SSL, passwordCleartext
    OUTGOING: , smtp.cox.net:465, SSL, passwordCleartext, true

  account4:
    INCOMING: account4, , (pop3) pop.cox.net:995, SSL, passwordCleartext
    OUTGOING: , smtp.cox.net:465, SSL, passwordCleartext, true

  account5:
    INCOMING: account5, , (pop3) pop.gmail.com:995, SSL, passwordCleartext
    OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

  account6:
    INCOMING: account6, , (pop3) pop.cox.net:995, SSL, passwordCleartext
    OUTGOING: , smtp.cox.net:465, SSL, passwordCleartext, true

Crash Reports

Extensions
  CompactHeader, 2.1.0, true, {58D4392A-842E-11DE-B51A-C7B855D89593}
  Lightning, 4.7.4, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}
  Messaging Menu and Unity Launcher integration, 1.3.1, true, messagingmenu@mozilla.com
  Silvermel and Charamel XT, 2.0.1, true, silvermelxt@pardal.de
  Get All Mail Button Thunderbird, 0.1, false, {0D4D76B0-657A-41b0-B3ED-60C638F4D97D}

Important Modified Preferences

  Name: Value

    browser.cache.disk.capacity: 358400
    browser.cache.disk.filesystem_reported: 1
    browser.cache.disk.smart_size_cached_value: 358400
    browser.cache.disk.smart_size.first_run: false
    browser.cache.disk.smart_size.use_old_max: false
    extensions.lastAppVersion: 45.5.1
    gfx.crash-guard.glcontext.appVersion: 45.5.1
    gfx.crash-guard.glcontext.deviceID: GeForce GT 555M/PCIe/SSE2
    gfx.crash-guard.glcontext.driverVersion: 4.5.0 NVIDIA 367.57
    gfx.crash-guard.status.glcontext: 2
    layers.acceleration.disabled: false
    mail.openMessageBehavior.version: 1
    mailnews.database.global.datastore.id: 63d477ea-ead8-4e70-a1b7-d30fea5925a
    network.cookie.prefsMigrated: true
    network.predictor.cleaned-up: true
    places.database.lastMaintenance: 1481677899
    places.history.expiration.transient_current_max_pages: 104858
    plugin.importedState: true

Graphics

    Adapter Description: NVIDIA Corporation -- GeForce GT 555M/PCIe/SSE2
    Vendor ID: NVIDIA Corporation
    Device ID: GeForce GT 555M/PCIe/SSE2
    Driver Version: 4.5.0 NVIDIA 367.57
    WebGL Renderer: NVIDIA Corporation -- GeForce GT 555M/PCIe/SSE2 -- 4.5.0 NVIDIA 367.57
    GPU Accelerated Windows: 0

    AzureCanvasBackend: cairo
    AzureSkiaAccelerated: 0
    AzureFallbackCanvasBackend: none
    AzureContentBackend: cairo
    CairoUseXRender: 1

JavaScript

Incremental GC: 1

Accessibility

  Activated: 0
  Prevent Accessibility: 0

Library Versions

    Expected minimum version
    Version in use

    NSPR
    4.12
    4.12

    NSS
    3.21.3 Basic ECC
    3.21.3 Basic ECC

    NSS Util
    3.21.3
    3.21.3

    NSS SSL
    3.21.3 Basic ECC
    3.21.3 Basic ECC

    NSS S/MIME
    3.21.3 Basic ECC
    3.21.3 Basic ECC

I've been using POP3 for over 20 years with many e-mail clients. I also set up systems for other people and want to recommend Thunderbird to people. If I can't get consistent results on my systems I definitely won't recommend it to anyone else. I worked at a local college at the help desk and in hardware support. I had MAC, Novell, and WIns systems to deal with as well as the newer Windows Server2003. We used Exchange server and Eudora. I have had to set up faculty and student mail. I have an IST degree. I am doing desktop support as a career. I wish you wouldn't assume things about me. I have legitimate issues with Thunderbird. If you can't parse my examples then maybe if you want clarification just ask but don't assume that my examples are pointless.

How is the log of your connection I asked for in your other duplicate thread going? https://support.mozilla.org/en-US/questions/1151754#answer-947273 No matter I will lock it. You can continue here.

Instead of wasting time complaining that we do not take you seriously and avoid the question, provide the information so we can investigate your issue.

We are not seeing the issue you are having. It you are not capable of providing sufficient information for someone to duplicate your experience then really it can only be something you or your provider are doing. My feeling it that there is some issue with the cox server, but without a log all I or anyone else can do is guess.

Are the issues with any specific email provider? I have zero experience with cox and am unlikely to be permitted an account to play with. However I have used Gmail with Thunderbird and POP and had zero problems, that is, apart from the inherent limitations of POP.

Thanks Zenos, I've been using Cox for the past 16 years. I have used other ISP's when setting up other people's accounts. Most of my customer's don't need to synchronize the number of accounts or systems. I'm giving up. I really appreciate you following up. I spend all day troubleshooting Windows and I don't have the time to waste with Thunderbird. I think anyone that wants to duplicate the problem could do it with any ISP and a couple computers with only one POP3 e-mail account. I should never have expected anyone to go to that much trouble. You have been helpful by not being so condescending like one of the other assholes from the Mozilla dungeon.

user1368925 said

Thanks Zenos, ...You have been helpful by not being so condescending like one of the other assholes from the Mozilla dungeon.

user1368925:

You don't provide the information we ask for, you treat us poorly, complain mightily, demand that things have to be only your way, refuse to accept change, and you use bad language.

Thus I conclude that you are not a support person yourself like you claim. If you really were a support person, you would not act this way.

I for one will be glad that you will not being using Thunderbird or asking any of us for help anymore.

It would appear that the posters account has been deactivated. I have no idea why, but the PM I got indicated he felt I was a waste of his time. Perhaps he was no so polite to someone else.