What are your outgoing smtp server settings? According to their website, they should be mail.uwclub.net on port 587, STARTTLS security (or port 465, SSL/TLS security), authentication = normal password, User name = email address.

Confirm you have a working password by logging onto their webmail, then check there are no obsolete passwords in Tools/Options/Security/Passwords/Saved Passwords.

server setting correct with port 465 security SSL/TLS, etc. Logged on to Utility Warehouse webmail, cannot find "Tools" button?

Confirm that Utility Warehouse webmail does not have a "Tools Button" available. Problem unresolved!

Look under Tools/Options/Security/Passwords/Saved Passwords in TB and remove any obsolete passwords. Press Alt if the Menu Bar with Tools is hidden.

Logged into Utility Warehouse webmail. Pressed Alt and displayed and found tools. There is no "options" toggle in the "tools" menu! By the way; assume "TB" stands for Tool Bar?

TB stands for Thunderbird. Look for Tools/Options in Thunderbird.

Ah! So it's Thunderbird you want me to check! Logged into Thunderbird, In "inbox" hit top right button for thunderbird menu. Found "tools", no "options" button available!

Tools/Options is on the Menu Bar. From the 'thunderbird menu', select Options/Options.

What "menu bar"? From what "thunderbird menu"? Look, I've been using Thunderbird for less than 48 hours. You are going to have to be a bit more specific if you want me to do the checks you require!

Thunderbird had a classic menu bar across the top but some genius decided to hide it and offer instead a button. You're using the button. You were advised to press the alt key in order to expose the old menu bar.

The old menu bar has a predictable, linear mode of operation. The new "application menu" behind the button responds in different ways depending on whether you click or hover, and indeed where you click. Regular contributors here on this forum tend to refer to the old menu bar.

But you were also told options|options which is (illogically) where you can find it in the application menu.

When I hit the Thunderbird icon on my desktop, the Thunderbird "inbox" window is displayed. Pressing [Alt] anywhere on the top of the screen has no effect. i.e. an old menu bar is not exposed. The new applications menu has no "options" selection.

I've been so wrapped up in the problem that maybe I've ignored the obvious. Thunderbird was installed as part of the Ubuntu 18-4 installation. I was only asked to create one password during the installation of Ubuntu. I did not have to create a password for Thunderbird. You wanted me to check for redundant passwords. Since I didn't input a password for Thunderbird, there won't be any.

DaveRhod said

I've been so wrapped up in the problem that maybe I've ignored the obvious. Thunderbird was installed as part of the Ubuntu 18-4 installation. I was only asked to create one password during the installation of Ubuntu. I did not have to create a password for Thunderbird. You wanted me to check for redundant passwords. Since I didn't input a password for Thunderbird, there won't be any.

How about you post the troubleshooting information. Then folks can stop guessing.

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)?

Trouble shooting information below. Problem persists in Thunbderbird safe mode. Have not loaded anti-virus or firewall software Utility Warehouse e-mail provider Firefox web browser Message in "sent error message" window says An error occurred while sending mail: Could not get password for mail.uwclub.net. The message was not sent. Immediate previous actions: In Thunderbird inbox, hit "write", wrote message to be sent. Hit "send" pop-up window SMTP Error Password required. Entered mail.uwclub.net password. popup window "login faIled" Hit "enter new password" button back to popup SMTP error Password popup. NOTE I am CERTAIN I entered the correct mail.uwclub.net password.

 Application Basics

   Name: Thunderbird
   Version: 52.9.1
   User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
   Profile Directory: Open Directory

             (Local drive)
   Application Build ID: 20180710084133
   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

   account4:
     INCOMING: account4, , (imap) mail.uwclub.net:993, SSL, passwordCleartext
     OUTGOING: , mail.uwclub.net:465, SSL, passwordCleartext, true

 Crash Reports

 Extensions
   Messaging Menu and Unity Launcher integration, 1.3.1, true, messagingmenu@mozilla.com

 Important Modified Preferences

   Name: Value

     browser.cache.disk.capacity: 358400
     browser.cache.disk.filesystem_reported: 1
     extensions.lastAppVersion: 52.9.1
     mail.openMessageBehavior.version: 1
     mailnews.database.global.datastore.id: 397d7bee-c7f8-4391-8838-a2d3ef25141
     media.gmp.storage.version.observed: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1531997392
     places.history.expiration.transient_current_max_pages: 122334

 Graphics

     GPU #1
     Description: Intel Open Source Technology Center -- Mesa DRI Intel(R) Sandybridge Desktop
     Vendor ID: Intel Open Source Technology Center
     Device ID: Mesa DRI Intel(R) Sandybridge Desktop
     Driver Version: 3.0 Mesa 18.0.5

     Features
     WebGL Renderer: Intel Open Source Technology Center -- Mesa DRI Intel(R) Sandybridge Desktop  -- 3.0 Mesa 18.0.5

     AzureCanvasBackend: skia
     AzureCanvasAccelerated: 0
     AzureFallbackCanvasBackend: none
     AzureContentBackend: skia
     CairoUseXRender: 0

 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

Not an answer to your problem, but it really does help to mention the OS when posting for help.

Yes, the details of the machine you posted on are made available. Your original post tells us:

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0

but that tell us about the machine you used when you posted the original query to this site. This isn't always necessarily the actual machine that has the problem!

This page: http://kb.mozillazine.org/Menu_differences_in_Windows,_Linux,_and_Mac is essential reading for those of us who choose to use non-mainstream operating systems. It will allow you to decipher the windows-centric advice found on many sites, including this one.

I only have one machine so same machine used for posting and has problem. I have read the menu differences article. It would appear the previous respondent assumed I was using windows and gave me instructions based on his assumption. A great pitty he didn't ask for the trouble shooting data and then when I advised that I couldn't find the "buttons" he asked me to use, he didn't then ask what OS i was using. It may have saved us all some time and effort!