I don't think I fully understand how Squirrelmail works. Can you explain 'as they were going through Squirrelmail still' in more detail?

Can you post your Thunderbird Troubleshooting Information? Help (Alt-H) - Troubleshooting Information

Sure. The emails were still being routed to my Squirrelmail email account and when I go to see them on Thunderbird they are not there. I can send an email from my Thunderbird but have tried and failed to get them to show up in my Thunderbird inbox instead of Squirrelmail.

The emails were still being routed to my Squirrelmail email account

This is the part I'm not sure about. Please post your Troubleshooting Information.

When I say routed I mean that the emails were only showing up in my Squirrelmail and not my Thunderbird, where ideally I'd like them to be in both. I'm not quite sure what you mean by "troubleshooting information" either. Maybe 30 minutes ago I was able to send and receive emails in Thunderbird just fine. I even received the notification from your response to my Thunderbird email. I came back to my computer and tried sending a test email from my Thunderbird to see if my boss' email had set up correctly and the outgoing stopped working saying:

"Sending of message failed. An error occurred sending mail: SMTP server smtp.easternglassblock.com is unknown. The server may be incorrectly configured. Please verify that your SMTP server settings are correct and try again."

I hadn't changed a thing once it was all started to work properly. I'm still receiving emails now but can no longer send at this moment.

Press Alt-H on your keyboard. From the help menu select Troubleshooting Information. Copy the whole thing and paste it into your reply.

Application Basics

   Name: Thunderbird
   Version: 24.6.0
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20140610001341
   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

   account7:
     INCOMING: account7, , (pop3) mail.easternglassblock.com:110, alwaysSTARTTLS, passwordCleartext
     OUTGOING: smtp.easternglassblock.com: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: 24.6.0
     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: 1402928994
     mailnews.database.global.datastore.id: 910294af-d906-45a8-8c98-42492c35030
     network.cookie.prefsMigrated: true
     places.database.lastMaintenance: 1402931156
     places.history.expiration.transient_current_max_pages: 101827
     plugin.importedState: true

 Graphics

     Adapter Description: Intel(R) HD Graphics
     Vendor ID: 0x8086
     Device ID: 0x0046
     Adapter RAM: Unknown
     Adapter Drivers: igdumd64 igd10umd64 igdumdx32 igd10umd32
     Driver Version: 8.15.10.2622
     Driver Date: 1-10-2012
     Direct2D Enabled: false
     DirectWrite Enabled: false (6.2.9200.16492)
     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

INCOMING: account7, , (pop3) mail.easternglassblock.com:110, alwaysSTARTTLS, passwordCleartext

Change 'Connection Security' to 'None' in your server settings for the incoming server. Check with your email provider whether a secure connection is supported, and if so, what the required settings are.

OUTGOING: smtp.easternglassblock.com:465, SSL, passwordCleartext, true

This should work. Just to be sure, in the settings for 'SMTP - Outgoing Server', select 'SSL/TLS' from the 'Connection security' dropdown.

Again, check with your email provider whether this is correct.

The outgoing server was on SSL/TLS when it was working before and is still on it now, which makes me wonder why it didn't work, then did work, then stopped working all within the same 15 minutes.

I'd suggest you check with your email provider easternglassblock.com.

Thanks for your help with all this