This message usually means that you have tried to send a message using an identity that isn't known to the SMTP server being used to send it.

In other words, if you have accounts A and B, and you're set up to send using A but send with "from B" then A's systems may object. Or maybe you have set up to use B's own servers, but your ISP refuses the connection to B's systems.

Easiest way to help you out is to see your settings. Help|Troubleshooting Information, uncheck "include account names" click "copy text to clipboard" Paste into your next reply here.

Application Basics

   Name: Thunderbird
   Version: 38.1.0
   User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20150707103124
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (imap) mail.dslextreme.com:993, SSL, passwordCleartext
     OUTGOING: smtp.dslextreme.com:465, SSL, none, true

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

 Crash Reports

 Extensions
   Extra Format Buttons, 1.3, true, [email protected]
   Image Zoom, 0.6.3.1-signed, true, {1A2D0EC4-75F5-4c91-89C4-3656F6E44B68}
   Lightning, 4.0.1, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}
   Toolbar Buttons, 1.1.1-signed, true, {03B08592-E5B4-45ff-A0BE-C1D975458688}

 Important Modified Preferences

   Name: Value

     browser.cache.disk.capacity: 358400
     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: 38.1.0
     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
     general.autoScroll: false
     gfx.direct2d.disabled: true
     gfx.direct3d.last_used_feature_level_idx: 0
     layers.acceleration.disabled: true
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 3a58b5c8-0a87-4411-912b-a3a5c5a2f80
     mailnews.database.global.views.conversation.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     network.cookie.cookieBehavior: 1
     network.cookie.lifetimePolicy: 1
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1437672984
     places.history.expiration.transient_current_max_pages: 104858
     plugin.importedState: true
     plugin.state.npwlpg: 2

 Graphics

     Adapter Description: Intel(R) HD Graphics 5500
     Vendor ID: 0x8086
     Device ID: 0x1616
     Adapter RAM: Unknown
     Adapter Drivers: igdumdim64 igd10iumd64 igd10iumd64 igdumdim32 igd10iumd32 igd10iumd32
     Driver Version: 10.18.14.4139
     Driver Date: 2-18-2015
     Direct2D Enabled: false
     DirectWrite Enabled: false (6.3.9600.17795)
     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: 1
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.10.8
     4.10.8

     NSS
     3.19.2 Basic ECC
     3.19.2 Basic ECC

     NSS Util
     3.19.2
     3.19.2

     NSS SSL
     3.19.2 Basic ECC
     3.19.2 Basic ECC

     NSS S/MIME
     3.19.2 Basic ECC
     3.19.2 Basic ECC

Thank you for any help. I am stumped. I am trying to use my new pc with Windows 8.1 and it is so user-UNfriendly pmjames

You have your SMTP server setup for Password = none.

You need to go into Account Settings, scroll to the bottom of the account list until you find Outgoing Server (SMTP) Enter that and edit the SMTP server settings to Password = Normal

pmjames said

When trying to send an email for the first time (new computer with windows 8.1) it gave me this error message: unable to send, Relay access denied.

I actually found that dslextreme is now using Zimbra so now I have no problems sending. Thank you