http://kb.mozillazine.org/Cannot_send_mail https://support.mozilla.org/en-US/kb/cannot-send-messages

Thanks finitarry, but I had already read those links and checked everything mentioned before I posted the first time. Still cannot send.

The error message reads ... "The message could not be sent using SMTP server smtp.cjhopkins.com for an unknown reason. Please verify that your SMTP server settings are correct and try again, or contact your network administrator."

Sorry to duplicate, but the reply I got to my first question didn't help, and there didn't seem to be any follow up. So I am trying to be more specific. I can receive but not send emails. I have read the page of suggested Mozilla solutions (Cannot send messages), tried them all, to no avail. I have contacted Network Solutions. Everything checks out their end. Disabling my anti-virus software does not help. I can send messages from a cell phone. As an experiment, I downloaded Opera, and tried it. I can send messages from Opera. But I don't want to use Opera. I want to use Thunderbird. The exact error message I get when trying to send is... "The message could not be sent using SMTP server XXXXX for an unknown reason. Please verify that your SMTP server settings are correct and try again, or contact your network administrator." I'd be very grateful for help with this.

A copy of the latest posting I closed.

To diagnose problems with Thunderbird, try one 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.

I neither of those resulted in a working outgoing arrangement, please add the troubleshooting information to your post. it is on the help menu under troubleshooting information, copy to clipboard and paste into a message here.

Thanks Matt. And apologies again for the duplicate posts. Unfortunately, neither of the two safe mode solutions changed anything. So here's the troubleshooting info.

 Application Basics

   Name: Thunderbird
   Version: 31.3.0
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20141127140543
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) mail.cjhopkins.com:110, plain, passwordCleartext
     OUTGOING: smtp.cjhopkins.com:587, alwaysSTARTTLS, passwordEncrypted, true

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

 Crash Reports

 Extensions

 Important Modified Preferences

   Name: Value

     accessibility.typeaheadfind.flashBar: 0
     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: 31.3.0
     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
     gfx.direct3d.last_used_feature_level_idx: 0
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: cf5d7c10-5d0b-43e4-a07f-37e0e1f98f1
     network.cookie.prefsMigrated: true
     places.database.lastMaintenance: 1419169933
     places.history.expiration.transient_current_max_pages: 104858
     plugin.importedState: true
     plugin.state.flash: 0
     plugin.state.npctrl: 0
     plugin.state.npdeployjava: 0
     plugin.state.npgoogleupdate: 0
     plugin.state.nppdf: 0
     plugin.state.npspwrap: 0
     plugins.update.notifyUser: true

 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: 8.15.10.2559
     Driver Date: 10-21-2011
     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
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: cairo

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.10.6
     4.10.6

     NSS
     3.16.2.3 Basic ECC
     3.16.2.3 Basic ECC

     NSS Util
     3.16.2.3
     3.16.2.3

     NSS SSL
     3.16.2.3 Basic ECC
     3.16.2.3 Basic ECC

     NSS S/MIME
     3.16.2.3 Basic ECC
     3.16.2.3 Basic ECC

The information in that list seems to be indicating that incoming mail is not encrypted, but outgoing is encrypted. That seems rather unusual. Have you got the correct setup for outgoing? Have you got the correct port number for SMTP?

Thanks finitarry, but yes, the outgoing settings are correct. In the meantime I have switched to eM Client, where everything is working just fine. I'd still like to know what went wrong with Thunderbird, however.

So, I still have no idea why my Thunderbird stopped being able to send emails (details above). I'm using eM Client, which works fine, but I'd rather be using Thunderbird, as I have for many years. If anyone can help, I'd be grateful...

what are the mail settings your internet host for mail.cjhopkins.com provided you with.

To diagnose problems with Thunderbird, try the following:

• 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.

Thanks Matt. The settings my host provided are as above. The same settings that are working fine in eM Client. I already tried the safe mode thing, as I mentioned before your earlier response, where you asked me to post all that data. No luck. I've also tried shutting down my AV software, and have scanned with an additional program for malware and viruses. No help. As I mentioned, other clients work fine, e.g. Opera and eM Client. Any other suggestions?

could you post a screen shot of those settings in EM client.

Seriously they look like a dogs breakfast. The incoming settings from about 15 or 20 years ago and the outgoing settings one would expect to see currently

jchopkins,com appears to be registered with Network solutions. See http://www.who.is/whois/jchopkins.com

I am also assuming that the hosting is occurring there. NEtwork solutions recommend settings see http://www.networksolutions.com/support/pop-imap-settings/

Outgoing Mail Server = smtp.yourdomain.com Outgoing Server Requires Authentication Do NOT check "Log on Using Secure Password Authentication"

   Use the same Username and Password as Incoming "

Outgoing Server Port = 2525 or 587

The Port is subject to change based on the individual preferences of your ISP if your with comcast use 587.

Based on that please go to Tools menu > account settings > outgoing server (SMTP) and change connection security to none. Authentication method to normal password and set the port based on your ISP.

cjhopkins said

I can receive but not send messages. My outgoing server settings are correct. The server (Network Solutions) is working fine. I changed the password there, no luck. I can send and receive from a cell phone. Grateful for prompt help.

Matt said

could you post a screen shot of those settings in EM client. Seriously they look like a dogs breakfast. The incoming settings from about 15 or 20 years ago and the outgoing settings one would expect to see currently jchopkins,com appears to be registered with Network solutions. See http://www.who.is/whois/jchopkins.com I am also assuming that the hosting is occurring there. NEtwork solutions recommend settings see http://www.networksolutions.com/support/pop-imap-settings/ Outgoing Mail Server = smtp.yourdomain.com Outgoing Server Requires Authentication Do NOT check "Log on Using Secure Password Authentication" Use the same Username and Password as Incoming " Outgoing Server Port = 2525 or 587 The Port is subject to change based on the individual preferences of your ISP if your with comcast use 587. Based on that please go to Tools menu > account settings > outgoing server (SMTP) and change connection security to none. Authentication method to normal password and set the port based on your ISP.

Thanks for sticking with me, Matt! It was indeed the outgoing security (none) and normal (unencrypted) password setting, just as you wrote above. Not sure how they got changed, but Thunderbird sending and receiving fine again now.

Just a final point, with the email settings you have, and even with more secure ones. Never commit to email anything you would not be prepared to write on a postcard and send snail mail. Standard email is transmitted around the web as plain text so if anyone is interested in your mail they can intercept and read it without any difficulty.

Thanks, yes, that has always been my assumption. Not sure how my settings got fouled up, as I didn't change them. The problem started after the last automatic mozilla update, but maybe that was correlation, rather than causation. In any event, it's fixed now. Many thanks again for your help!