I started writing a reply to this. But really I have no idea where to start.

You speak like there is some mystery about locating the archive folder. The image below is of one of my accounts in the folder pane. Can you locate the archive folder in hat? It is just another folder.

My guess and with the serious lack of information I am guessing. I think your windows live mail is downloading the mail from the server using the POP mail protocol and removing the mail from Thunderbird which will have defaulted to use IMAP which is synchronized to the mail server. So each time you open live mail all the mail that has arrived since the last time you did it is downloaded to live mail and removed from the server (and Thunderbird) by your action.

i'm so glad that your email already has the archive folder for you to use. mine did not. i had to add it myself & then figure out how to get things to go to it which only catches the sent items now.

this did not help me with finding the emails that you think may have been eaten up by live mail from the server. if me opening live mail is making emails disappear from thunderbird, then why don't they all disappear? no, this issue has to do with the oldest emails falling off the bottom of then list whenever i get a new email. for example, just before i started writing this reply i had an email dated 8-1-2018 as the oldest. i received a new email 15 minutes ago & now the oldest email on my list is from 8-3-2018. where did the 8-1-2018 email go? how to i get it back? what about all the prior emails from july - where are they? i want to keep all of my emails in my inbox until i move them myself. is there a way to make my inbox keep every single one of my emails?

please remember not all of us are tech people. yes, i checked the box to keep all on local computer - it didn't. my server is set up to only keep them for a limited amount of time because i like to keep them local. once the emails are opened on my computer, the server doesn't keep it any longer than a week because that's the way i want it. is thunderbird storing my disappearing emails back on my server? if so, how do i tell it not to? live mail didn't disappear messages back to the server & i was hoping that thunderbird would work the same way.

just f.y.i. - since writing this response, my oldest email in my inbox is now 8-6-2018.

Please add the troubleshooting information to your post To find the Troubleshooting information:

• Open Help (or click on three-line-icon and select Help)
• Choose Troubleshooting Information
• Use the button Copy to clipboard to select all. Do not check box "Include account names"!
• Paste this in your post.

Application Basics

   Name: Thunderbird
   Version: 52.9.1
   User Agent: Mozilla/5.0 (Windows NT 6.1; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
   Profile Folder: Open Folder

             (Local drive)
   Application Build ID: 20180709124824
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory
   Profiles: about:profiles

 Mail and News Accounts
   account1:
     INCOMING: account1, , (imap) mail.truettcarpetsandrugs.com:143, alwaysSTARTTLS, passwordCleartext
     OUTGOING: , mail.truettcarpetsandrugs.com:587, alwaysSTARTTLS, passwordCleartext, true

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

 Crash Reports

 Extensions
   ImportExportTools, 3.3.0, true, {3ed8cc52-86fc-4613-9026-c1ef969da4c3}
   Lightning, 5.4.9.1, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}
   MoreFunctionsForAddressBook, 1.0b7, true, {3e17310d-82e8-4a43-bd2f-7c3055bfe589}

 Important Modified Preferences

   Name: Value

     browser.cache.disk.capacity: 358400
     browser.cache.disk.filesystem_reported: 1
     extensions.lastAppVersion: 52.9.1
     font.name.monospace.el: Consolas
     font.name.monospace.x-cyrillic: Consolas
     font.name.monospace.x-unicode: Consolas
     font.name.monospace.x-western: Consolas
     font.name.sans-serif.el: Calibri
     font.name.sans-serif.x-cyrillic: Calibri
     font.name.sans-serif.x-unicode: Calibri
     font.name.sans-serif.x-western: Calibri
     font.name.serif.el: Cambria
     font.name.serif.x-cyrillic: Cambria
     font.name.serif.x-unicode: Cambria
     font.name.serif.x-western: Cambria
     font.size.fixed.el: 14
     font.size.fixed.x-cyrillic: 14
     font.size.fixed.x-unicode: 14
     font.size.fixed.x-western: 14
     font.size.variable.el: 17
     font.size.variable.x-cyrillic: 17
     font.size.variable.x-unicode: 17
     font.size.variable.x-western: 17
     gfx.blacklist.direct2d: 3
     gfx.blacklist.direct2d.failureid: FEATURE_FAILURE_DL_BLACKLIST_g984
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 64cc8ce0-49a7-43a2-850c-3c6b931a38b
     media.gmp.storage.version.observed: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1534776748
     places.history.expiration.transient_current_max_pages: 122334
     security.sandbox.content.tempDirSuffix: {84bacd98-311b-4032-916f-7af3f2510adb}

 Graphics

     GPU #1
     Description: Intel(R)  Q965/Q963 Express Chipset Family
     Vendor ID: 0x8086
     Device ID: 0x2992
     RAM: Unknown
     Drivers: igdumdx32
     Driver Version: 8.15.10.1930
     Driver Date: 9-23-2009

     Features
     Direct2D: Blocked for your graphics driver version.
     DirectWrite: true (6.2.9200.22164)
     WebGL Renderer: Google Inc. -- ANGLE (Software Adapter Direct3D11 vs_5_0 ps_5_0) -- OpenGL ES 2.0 (ANGLE 2.1.0.2a250c8a0e15)

     AzureCanvasBackend: skia
     AzureCanvasAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: skia

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.13.1
     4.13.1

     NSS
     3.28.6
     3.28.6

     NSS Util
     3.28.6
     3.28.6

     NSS SSL
     3.28.6
     3.28.6

     NSS S/MIME
     3.28.6
     3.28.6

my inbox holds 110 emails at a time. anything more than that, whether it is starred or not, gets dropped out of the inbox. where does it go? it does not go into my archive folder. i have the box checked to save them all to my local computer. how do i get them back? i can't use an email service that hides all my emails after it thinks i'm done with them. doesn't anyone else have this problem? does no one else ever need to refer back to an email from a month ago? what about people who receive hundreds of emails every day? i was going to suggest my coworkers switch from windows live mail to thunderbird, but i don't even want to keep using it myself unless someone can help me with this. i was starting to get used to thunderbird & liked most of what it offers, but then i started to think i was going insane because i suddenly couldn't find emails that i knew i had received.

please give me some help.