For both, Sent and Draft folders it looks like there is some sort of corruption. First of all create a backup of your Thunderbird profile folder. https://support.mozilla.org/kb/profiles-tb#w_backing-up-a-profile

Then try to rebuild the index file of the troubled folder. Right-click the folder - Properties - Repair Folder

Note: depending on the corruption this may erase messages from the affected folder which cannot be recovered anymore. In that case you'd need to restore them from a recent backup done prior to the corruption.

Corruption is often caused by anti-virus software messing with Thunderbird mail files. It is therefore recommended to create an exception for the Thunderbird profile folder, so that the real-time scanner won't attempt to scan the profile with your mail.

For more information on the profile location see http://kb.mozillazine.org/Profile_folder_-_Thunderbird

Also see http://kb.mozillazine.org/Keep_it_working_-_Thunderbird

Thanks for you response. I have done the "repair" thing and draft folder has been fixed. As for "sent" folder the list of sent messages is now full and up to date, however the content is still not available.

Can you try to move one of the messages where the content doesn't show to another folder, e.g. underneath 'Local Folders'? Does the content of the message become visible?

It's not possible to move messages from "Sent" folder to local folder. It is however possible to move there messages from "Inbox".

It's not possible to move messages from "Sent" folder to local folder.

Why not?

It's not possible to move messages from "Sent" to local folder because drag&drop operation has no effect. Also there is no error message of any kind.

Did you exclude the Thunderbird profile folder from being scanned by your anti-virus software as suggested above?

Try to start Windows in safe mode with networking enabled. - Win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

Still in Windows safe mode, start Thunderbird in safe mode. - https://support.mozilla.org/kb/safe-mode

Can you now move messages from 'Sent' to 'Local Folders'?

Hi, I have added profile folder to scanning exceptions in my antivirus. I have also started Windows 10 in safe mode with networking and while in safe mode I started thunderbird in safe mode. Still cannot read or move messages from 'Sent' folder to any of 'Local folders'. I only see the message on status bar saying "Sent Downloading message header 1 of 48..."

Double check: right click on imap mail account in Folder Pane and select 'Subscribe' Select: server imap 'Sent' folder. click on 'UnSubscribe' click on OK then repeat process to 'Subscribe' to see 'Sent' folder.

check Account Settings

• right click on imap mail account in Folder Pane and select 'Settings'
• select 'Copies & Folders' for imap mail account

When sending messages, automatically:

• select: 'Place a copy in'
• Select 'Other' and choose the 'Sent' folder on imap mail account.

• Select: 'Synchronisation & Storage'
• Do not select: 'don't download messages larger than...'

Do you want to keep copies of messages in profile? 'Message synchronisation'

• select: 'keep messages for this account on this computer'
• or click on 'Advanced' button to select folders.

• Select; 'Synchronise all messages locallyregardless of age'
• click on OK

Exit Thunderbird. Wait a few moments for processes to complete. Start thunderbird.

Select 'Sent' folder.

Please report back on results.

Hello, thanks for instruction. I have done all above settings. It's not possible to unsubscribe and subscribe 'sent' folder because even if I untick that folder and press OK it stays enabled. It's not possible to unsubscribe any of folders. When I open sent folder I see green progress bar at the very beginning of that bar but not progressing at all.

Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button , then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

Application Basics

   Name: Thunderbird
   Version: 52.2.1
   User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1
   Profile Folder: Open Folder

             (Local drive)
   Application Build ID: 20170622064432
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory
   Profiles: about:profiles

 Mail and News Accounts
   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account3:
     INCOMING: account3, , (imap) imap.poczta.onet.pl:993, SSL, passwordCleartext
     OUTGOING: , smtp.poczta.onet.pl:465, SSL, passwordCleartext, true

 Crash Reports

 Extensions
   Lightning, 5.4.2.1, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Important Modified Preferences

   Name: Value

     accessibility.typeaheadfind.flashBar: 0
     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
     dom.apps.reset-permissions: true
     extensions.lastAppVersion: 52.2.1
     font.internaluseonly.changed: false
     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
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 5cba611d-a56b-4dd4-afae-e62f66dd8ef
     media.gmp.storage.version.observed: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1498222917
     places.history.expiration.transient_current_max_pages: 122334
     plugin.importedState: true
     privacy.sanitize.timeSpan: 0
     security.sandbox.content.tempDirSuffix: {bd39cdaf-51b4-48c7-9259-067bc4a47cd9}

 Graphics

     GPU #1
     Description: NVIDIA GeForce GTX 1070
     Vendor ID: 0x10de
     Device ID: 0x1b81
     RAM: 8192
     Drivers: C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvd3dumx,C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvwgf2umx,C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvwgf2umx,C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvwgf2umx C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvd3dum,C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvwgf2um,C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvwgf2um,C:\Windows\System32\DriverStore\FileRepository\nv_dispi.inf_amd64_0cc477a6fec64d8c\nvwgf2um
     Driver Version: 21.21.13.7866
     Driver Date: 2-9-2017

     Features
     Direct2D: false
     DirectWrite: true (10.0.14393.1358)
     ClearType Parameters: Gamma: 2.2 Pixel Structure: BGR ClearType Level: 0 Enhanced Contrast: 50
     WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GTX 1070 Direct3D9Ex vs_3_0 ps_3_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
     3.28.5
     3.28.5

     NSS Util
     3.28.5
     3.28.5

     NSS SSL
     3.28.5
     3.28.5

     NSS S/MIME
     3.28.5
     3.28.5

There are no additional clues from the Troubleshooting Information.

Not much more to suggest other than creating a new profile and set-up your account again in the new profile. https://support.mozilla.org/en-US/kb/using-multiple-profiles

I created new profile and the problem persists with following error in log:

2017-06-30 19:45:24 autosyncActivities ERROR OnDownloadError: Sent of myemailaddress@domain.pl

 log4moz.js:691

CApp_append resource:///modules/gloda/log4moz.js:691:7 Logger_log resource:///modules/gloda/log4moz.js:380:7 Logger_error resource:///modules/gloda/log4moz.js:388:5 autosyncModule.onDownloadError resource:///modules/activity/autosync.js:324:7 appIdleManager._timerCallback

Clear the browser cache and the Windows Temp directory. Shutdown any anti-virus software you are running. Download a new copy of Thunderbird from here:

• https://www.mozilla.org/en-US/thunderbird/all/

On computer, delete the 'Mozilla Thunderbird' directory: If running Windows OS 64bit: C:\Program Files (x86)\Mozilla Thunderbird If running Windows OS 32bit: C:\Program Files\Mozilla Thunderbird

Run the downloaded installer program to install Thunderbird. Restart the anti-virus program.