https://support.mozilla.org/kb/cannot-send-messages

Problem not solved.

Which troubleshooting steps mentioned in the article did you do, and what was the result?

I tried all the suggstions posted on the Help pages and none of them worked.

Since I updated the mail software and changed my password, Thunderbird no longer sends emails

What exactly prevents you from sending messages?

Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button , then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

Troubleshooting Information This page contains technical information that might be useful when you're trying to solve a problem. If you are looking for answers to common questions about Thunderbird, check out our support web site. Include account names (possibly identifying information) Application Basics Name Thunderbird Version 52.5.2 User Agent Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 Profile Folder (Local drive) Application Build ID 20171221110448 Enabled Plugins about:plugins Build Configuration about:buildconfig Memory Use about:memory Profiles about:profiles Mail and News Accounts ID Incoming server Outgoing servers Name Connection security Authentication method Name Connection security Authentication method Default? account1 (imap) mail.btinternet.com:993 SSL/TLS Normal password mail.btinternet.com:465 SSL/TLS Normal password true account2 (none) Local Folders None Normal password account3 (imap) mail.btinternet.com:993 SSL/TLS Normal password mail.btinternet.com:465 SSL/TLS Normal password true account4 (imap) mail.btinternet.com:993 SSL/TLS Normal password mail.btinternet.com:465 SSL/TLS Normal password true Crash Reports Report ID Submitted

All Crash Reports Extensions Name Version Enabled ID Lightning 5.4.5.2 true {e2fda1a4-762b-4020-b5ad-a41df1933103} Important Modified Preferences Name Value accessibility.lastLoadDate 1514975057 accessibility.typeaheadfind.flashBar 0 browser.cache.disk.capacity 358400 browser.cache.disk.filesystem_reported 1 extensions.lastAppVersion 52.5.2 font.internaluseonly.changed false 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 mail.openMessageBehavior.version 1 mail.winsearch.firstRunDone true mailnews.database.global.datastore.id 54cd7903-49e4-44d2-82c5-eba5b5a1c9a 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… media.gmp.storage.version.observed 1 network.cookie.prefsMigrated true network.predictor.cleaned-up true places.database.lastMaintenance 1514725056 places.history.expiration.transient_current_max_pages 122334 print.printer_Canon_MX470_series_Printer.print_bgcolor false print.printer_Canon_MX470_series_Printer.print_bgimages false print.printer_Canon_MX470_series_Printer.print_duplex -437918235 print.printer_Canon_MX470_series_Printer.print_edge_bottom 0 print.printer_Canon_MX470_series_Printer.print_edge_left 0 print.printer_Canon_MX470_series_Printer.print_edge_right 0 print.printer_Canon_MX470_series_Printer.print_edge_top 0 print.printer_Canon_MX470_series_Printer.print_evenpages true print.printer_Canon_MX470_series_Printer.print_footercenter print.printer_Canon_MX470_series_Printer.print_footerleft &PT print.printer_Canon_MX470_series_Printer.print_footerright &D print.printer_Canon_MX470_series_Printer.print_headercenter print.printer_Canon_MX470_series_Printer.print_headerleft &T print.printer_Canon_MX470_series_Printer.print_headerright &U print.printer_Canon_MX470_series_Printer.print_in_color true print.printer_Canon_MX470_series_Printer.print_margin_bottom 0.5 print.printer_Canon_MX470_series_Printer.print_margin_left 0.5 print.printer_Canon_MX470_series_Printer.print_margin_right 0.5 print.printer_Canon_MX470_series_Printer.print_margin_top 0.5 print.printer_Canon_MX470_series_Printer.print_oddpages true print.printer_Canon_MX470_series_Printer.print_orientation 0 print.printer_Canon_MX470_series_Printer.print_page_delay 50 print.printer_Canon_MX470_series_Printer.print_paper_data 9 print.printer_Canon_MX470_series_Printer.print_paper_height -1.00 print.printer_Canon_MX470_series_Printer.print_paper_name print.printer_Canon_MX470_series_Printer.print_paper_size_unit 1 print.printer_Canon_MX470_series_Printer.print_paper_width -1.00 print.printer_Canon_MX470_series_Printer.print_resolution 600 print.printer_Canon_MX470_series_Printer.print_reversed false print.printer_Canon_MX470_series_Printer.print_scaling 1.00 print.printer_Canon_MX470_series_Printer.print_shrink_to_fit true print.printer_Canon_MX470_series_Printer.print_to_file false print.printer_Canon_MX470_series_Printer.print_unwriteable_margin_bottom 0 print.printer_Canon_MX470_series_Printer.print_unwriteable_margin_left 0 print.printer_Canon_MX470_series_Printer.print_unwriteable_margin_right 0 print.printer_Canon_MX470_series_Printer.print_unwriteable_margin_top 0 security.sandbox.content.tempDirSuffix {1b44c487-1ae7-4545-96f5-de2ab9583c6e} Graphics GPU #1 Description Intel(R) HD Graphics 620 Vendor ID 0x8086 Device ID 0x5916 RAM Unknown Drivers igdumdim64 igd10iumd64 igd10iumd64 igd12umd64 igdumdim32 igd10iumd32 igd10iumd32 igd12umd32 Driver Version 21.20.16.4550 Driver Date 11-11-2016 Features Direct2D false DirectWrite true (10.0.16299.15) WebGL Renderer Google Inc. -- ANGLE (Intel(R) HD Graphics 620 Direct3D9Ex vs_3_0 ps_3_0) -- OpenGL ES 2.0 (ANGLE 2.1.0.2a250c8a0e15) AzureCanvasBackend skia AzureCanvasAccelerated 0 AzureFallbackCanvasBackend cairo AzureContentBackend skia 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

Your server settings look good.

Once again: What exactly prevents you from sending messages?

What is your antivirus software?

When I press send I get "Connected to mail.btinternet.com" but nothing happens - the mail does not get sent.

When I send a test mail to myself from my wife's identity ([email protected]) that works.

When I try from a third identity - [email protected] - same as for mine i.e. sending fails.

Anti virus is Sophos (free version)

Try to start Windows in safe mode with networking enabled. - Win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

Still in Windows safe mode, start Thunderbird in safe mode. - https://support.mozilla.org/kb/safe-mode

Does the problem go away?

Went into safe mode with networking (5) and copied/pasted the second link into my Firefox browser but it was not recognised i.e. the site could not be found. What next?

If you're using WLAN this may get disabled in safe mode. Use a wired connection instead.

Can't do this as I don't have a wired facility.

I really don't know how to get this fixed. I've tried changing my passord and have checked via webmail that it's working OK. I can still send test messages to my email address from [email protected] which is on the same thunderbird platform, but not from jlb.mail@btinternet.

It is quite common that anti-virus software interferes with Thunderbird. Windows safe mode disables anti-virus software, hence the suggestion.

Some general suggestions wrt anti-virus software: Create an exception in your anti-virus software for the Thunderbird profile folder, so that the anti-virus real-time scanner will not scan it. http://kb.mozillazine.org/Profile_folder_-_Thunderbird

Don't let your anti-virus software scan incoming and outgoing messages.

Don't let your anti-virus software scan attachments.

Don't let your anti-virus software intercept your secure connection to the server.

Remove any add-ons your anti-virus software may have installed in Thunderbird.

Keep it working. http://kb.mozillazine.org/Keep_it_working_-_Thunderbird

And last but not least, backup your Thunderbird profile on a regular basis. https://support.mozilla.org/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

Also see https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues

I'm sorry to have to stop using Thunderbird due to the fact that, in spite of every effort on your behalf, no solution worked.

You have three mail accounts in Thunderbird. Each one will be for a different email address. How many Outgoing servers (SMTP) do you have? Right click on mail account and select 'Settings' Bottom left click on 'Outgoing Server (SMTP) You should have three outgoing servers, one for each email address.

Do you have three? click on first one to see details. You will know which one it is because the User Name = full email address. Click on 'Edit' In the 'Description' field enter something of use eg: the email address. Make sure the User Name = full email address. click on OK

Do the same for all other outgoing servers.

Then check each mail account is using the correct outgoing server. select the mail account name is left pane. bottom right will say 'Outgoing server (SMTP)' click ondrop down and select the one where the Description email address is the correct one for the maila ccount. Repeat for all other mail accounts.

Confirm that all mail accounts are using their own unique outgoing server.