Yahoo is trying to invent email security and force people into using their site directly. Read this and see if it helps. https://help.yahoo.com/kb/SLN27791.html

thank you ! i'll have a look and see what i can do !

hello,

i had a look but it didn't help. Beside i can receive mails i just can't send them. 

I got an error message attached. I think it s a problem with thundirbirds but i am not sure why as it has always worked before and it happens after having used my mail directly from the yahoo site.

Has anyone had this problem before ? 

thank you for your help ! Sand

It sounds like something may be wrong with either 'Connection Security' or 'Authentication Method'.

Please post the following information: In Thunderbird Help > Troubleshooting information click on 'Copy text to clipboard' button

in this forum question, right click in a 'Post a Reply' text box and select 'Paste' You can remove all the info on fonts and printers but nothing else.

Hello Thank you ! It is ok to post this information on a public site ?

Only one thing to check: Before clicking on 'Copy text to clipboard', make sure 'Include account names' is NOT selected. See image below. Otherwise all the data is only server details - nothing personal, so it is ok to post.

Ok, thank you !

 Application Basics

   Name: Thunderbird
   Version: 45.6.0
   User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:45.0) Gecko/20100101 Thunderbird/45.6.0
   Profile Folder: Show in Finder
   Application Build ID: 20161222195647
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) pop.mail.yahoo.com:995, SSL, passwordCleartext
     OUTGOING: , smtp.mail.yahoo.com:465, SSL, none, true

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

 Crash Reports

 Extensions
   Lightning, 4.7.6, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Important Modified Preferences

   Name: Value

     accessibility.typeaheadfind.flashBar: 0
     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
     extensions.lastAppVersion: 45.6.0
     gfx.blacklist.direct2d: 3
     gfx.crash-guard.glcontext.appVersion: 45.6.0
     gfx.crash-guard.glcontext.deviceID: 0x0d26
     gfx.crash-guard.status.glcontext: 2
     mail.openMessageBehavior.version: 1
     mail.spotlight.firstRunDone: true
     mailnews.database.global.datastore.id: 47faa1f2-ad49-f242-92a8-bef37b514bf
     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.cookieBehavior: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1485179790
     places.history.expiration.transient_current_max_pages: 104858
     plugin.importedState: true
     privacy.donottrackheader.enabled: true
     security.disable_button.openCertManager: false

 Graphics

     Vendor ID: 0x8086
     Device ID: 0x0d26
     WebGL Renderer: Intel Inc. -- Intel Iris Pro OpenGL Engine -- 2.1 INTEL-10.6.33
     GPU Accelerated Windows: 0

     AzureCanvasBackend: skia
     AzureSkiaAccelerated: 1
     AzureFallbackCanvasBackend: none
     AzureContentBackend: quartz

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   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

Since you have your smtp set to not provide a password it is no wonder that it fails authentication.

Go into your smtp setting and change Authentication Method from None to Normal Password.

Agree with 'Airmail'.

re :OUTGOING: , smtp.mail.yahoo.com:465, SSL, none, true

this means you are not sending a password, so you are getting the pop up 5.7.1 Authentication Failed error.

• Right click on mail account in Folder pane and select 'Settings'
• Bottom Left - select 'Outgoing server (SMTP)'

on the right you will see a list of your outgoing servers.

• select the smtp server
• click on 'Edit'
• Authentication method: select 'Normal Password'
• click on all 'OK's

It's working ! thank you so much ! That's so great! No idea why this changed but I m glad that it's fixed! Thank you