Problems with mail servers and the internet are vaguely connected. It is a bit like telling me that your television is fine because the lights are still on in your house. Both use electricity.

To diagnose problems with Thunderbird, try both of the following:

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.
• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

This does not help with problem

have you done it?

YES! I tried before you made the suggestion, and again afterwards. i would not be telling you it doesn't work if I had not done it!

Now you tell me it does not work. Before you tried "this does not help" to me a completely meaningless statement.

So let me get this right. You have multiple mail accounts in Thunderbird. They all stopped working at the same time. Restarting Your operating system in Safe mode with Networking does not fix the problem.

Well all that is left is your setting on the mail server or a third part blocking access via a router of DNS issue We know Thunderbird works. (it is a given there are 6 people complaining here not 6 million) We know it is not your anti virus or firewall as you tried safe mode.

So please post your troubleshooting information.

Click the Help menu (Alt+H) at the top and select Troubleshooting Information from the menu. Now, a new tab containing your troubleshooting information should open.

• At the top of the page, you should see a button that says "Copy text to clipboard". Click it.
• Now, go back to your forum post and click inside the reply box. Press Ctrl+V to paste all the information you copied into the forum post.

Application Basics

   Name: Thunderbird
   Version: 24.5.0
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20140424091057
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Crash Reports: about:crashes
   Memory Use: about:memory

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

   account3:
     INCOMING: account3, , (pop3) pop.gmail.com:995, SSL, passwordCleartext
     OUTGOING: smtp.umn.edu:465, SSL, passwordCleartext, true

 Extensions

 Important Modified Preferences

   Name: Value

     browser.cache.disk.capacity: 358400
     browser.cache.disk.smart_size.first_run: false
     browser.cache.disk.smart_size.use_old_max: false
     browser.cache.disk.smart_size_cached_value: 358400
     extensions.lastAppVersion: 24.5.0
     font.internaluseonly.changed: false
     font.name.monospace.el: Consolas
     font.name.monospace.tr: Consolas
     font.name.monospace.x-baltic: Consolas
     font.name.monospace.x-central-euro: 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.tr: Calibri
     font.name.sans-serif.x-baltic: Calibri
     font.name.sans-serif.x-central-euro: 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.tr: Cambria
     font.name.serif.x-baltic: Cambria
     font.name.serif.x-central-euro: 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.tr: 14
     font.size.fixed.x-baltic: 14
     font.size.fixed.x-central-euro: 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.tr: 17
     font.size.variable.x-baltic: 17
     font.size.variable.x-central-euro: 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.enable: true
     mail.winsearch.firstRunDone: true
     mail.winsearch.global_reindex_time: 1321142086
     mailnews.database.global.datastore.id: ba9c16f0-d125-44df-86a6-989fdee0406
     network.cookie.prefsMigrated: true
     places.database.lastMaintenance: 1398912551
     places.history.expiration.transient_current_max_pages: 104858
     places.history.expiration.transient_optimal_database_size: 167772160
     plugin.importedState: true
     plugins.update.notifyUser: true
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_bgcolor: false
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_bgimages: false
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_colorspace:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_command:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_downloadfonts: false
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_duplex: 4063349
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_edge_bottom: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_edge_left: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_edge_right: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_edge_top: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_evenpages: true
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_footercenter:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_footerleft: &PT
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_footerright: &D
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_headercenter:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_headerleft: &T
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_headerright: &U
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_in_color: true
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_margin_bottom: 0.5
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_margin_left: 0.5
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_margin_right: 0.5
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_margin_top: 0.5
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_oddpages: true
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_orientation: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_page_delay: 50
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_paper_data: 1
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_paper_height: 11.00
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_paper_name:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_paper_size_type: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_paper_size_unit: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_paper_width: 8.50
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_plex_name:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_resolution: 6553701
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_resolution_name:
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_reversed: false
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_scaling: 1.00
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_shrink_to_fit: true
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_to_file: false
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_unwriteable_margin_bottom: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_unwriteable_margin_left: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_unwriteable_margin_right: 0
     print.printer_Brother_MFC-7860DW_Printer_(Copy_1).print_unwriteable_margin_top: 0

 Graphics

     Adapter Description: Intel(R) HD Graphics Family
     Vendor ID: 0x8086
     Device ID: 0x0116
     Adapter RAM: Unknown
     Adapter Drivers: igdumd64 igd10umd64 igd10umd64 igdumdx32 igd10umd32 igd10umd32
     Driver Version: 8.15.10.2342
     Driver Date: 3-25-2011
     Adapter Description (GPU #2): NVIDIA GeForce GT 525M
     Vendor ID (GPU #2): 0x10de
     Device ID (GPU #2): 0x0df5
     Adapter RAM (GPU #2): 1024
     Adapter Drivers (GPU #2): nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
     Driver Version (GPU #2): 9.18.13.3523
     Driver Date (GPU #2): 3-4-2014
     Direct2D Enabled: false
     DirectWrite Enabled: false (6.2.9200.16571)
     ClearType Parameters: ClearType parameters not found
     WebGL Renderer: false
     GPU Accelerated Windows: 0

     AzureCanvasBackend: skia
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: none

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.10.2
     4.10.2

     NSS
     3.15.4 Basic ECC
     3.15.4 Basic ECC

     NSS Util
     3.15.4
     3.15.4

     NSS SSL
     3.15.4 Basic ECC
     3.15.4 Basic ECC

     NSS S/MIME
     3.15.4 Basic ECC
     3.15.4 Basic ECC