Given Mozilla do not have a support line, you may well have been talking to the CEO or the chairman of the board. One thing I can guarantee, it was not scrip jockey from a support line.

Now the second part of your problem is Mozilla do not support Thunderbird anymore. We are a community project.

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.

Please also add the result of these troubleshooting steps to your post

• Does Thunderbird work in TB Safe mode (see Thunderbird Safe Mode)?
• Do you use anti-virus and firewall software? What is the version?
• Who is the email provider?
• Who is the internet provider?
• What is the exact error message?

Thanks, Matt - here you go. Results of copy and paste:

 Application Basics

   Name: Thunderbird
   Version: 45.5.1
   User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20161130024037
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

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

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

 Crash Reports

 Extensions
   Lightning, 4.7.5.1, false, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Important Modified Preferences

   Name: Value

     accessibility.lastLoadDate: 1484537054
     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: 45.5.1
     font.internaluseonly.changed: true
     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.crash-guard.glcontext.appVersion: 45.5.1
     gfx.crash-guard.glcontext.deviceID: 0x1616
     gfx.crash-guard.glcontext.driverVersion: 20.19.15.4377
     gfx.crash-guard.glcontext.gfx.driver-init.direct3d11-angle: true
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle: true
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-d3d11: false
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-warp: false
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-try-d3d11: true
     gfx.crash-guard.status.glcontext: 2
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 03f11949-877c-49e0-8f8a-ecda0fc925d
     mailnews.database.global.views.conversation.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     mailnews.database.global.views.global.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1484517339
     places.history.expiration.transient_current_max_pages: 104858
     plugin.importedState: true
     plugin.state.flash: 0

 Graphics

     Adapter Description: Intel(R) HD Graphics 5500
     Vendor ID: 0x8086
     Device ID: 0x1616
     Adapter RAM: Unknown
     Adapter Drivers: igdumdim64 igd10iumd64 igd10iumd64 igd12umd64 igdumdim32 igd10iumd32 igd10iumd32 igd12umd32
     Driver Version: 20.19.15.4377
     Driver Date: 1-25-2016
     Direct2D Enabled: false
     DirectWrite Enabled: false (10.0.14393.351)
     ClearType Parameters: ClearType parameters not found
     WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics 5500 Direct3D11 vs_5_0 ps_5_0) -- OpenGL ES 2.0 (ANGLE 2.1.0.316930d51ea9)
     GPU Accelerated Windows: 0

     AzureCanvasBackend: skia
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: cairo

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 1
   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

END OF RESULTS Does Thunderbird work in TB Safe mode (see Thunderbird Safe Mode)? NO Do you use anti-virus and firewall software? What is the version? Norton Who is the email provider? Time Warner Cable/Spectrum Who is the internet provider? Google Chrome What is the exact error message? I'm no longer getting an error message, cable fixed that. Now it just spins, as if it's refreshing, but nothing happens.

Hope that helps. Not thrilled that there is no actual customer service but really appreciate your time.

Regards, Linda

lets start with the obvious and work from there.

TWC settings per TWC https://www.timewarnercable.com/en/support/faqs/faqs-internet/e-mailacco/incoming-outgoing-server-addresses.html

Those settings do not use SSL. so perhaps a good starting point is to reduce the connection security to none. I do not know why we have SSL and STARTTLS in use of TWC do not recommend it.

Next, turn off Norton's mail scanner. As your account is IMAP it does not scan mail anyway, but it sure can scramble the connection and mail reception.

Finally check the Norton firewall that Thunderbird Version 45.5.1 is allowed through the firewall. Norton is very sensitive to version numbers. changing even the last one to a 2 would be enough to make it choke on it's coffee and block Thunderbird as unknown.

It worked, Matt! Thank you so much. Have a great day.

Regards, Linda