Cannot setup Thunderbird for my @prodigy.net email account, which goes through Yahoo.com and at&t

I ... got it to work as POP3 for about 5 days

Please describe in detail the steps you did to set up the account in Thunderbird. Did you use the Thunderbird Account Hub with automatic account setup, or manual configuration?

Last week I had to enter a passkey in as the password

How exactly did you create the passkey? Thunderbird doesn't support passkeys, so this can only be done in a web browser.

This week I have tried the same passkey as "Normal Password"

Please explain what that means. Passkeys and passwords are not the same thing, and are not interchangeable. https://www.passkeys.io/

I thought I might change the passkey, but now I cannot FIND how to change, remove or create a passkey.

You can create a passkey in your Yahoo Account Settings - Security. There is no point changing a passkey though. https://login.yahoo.com/account/personalinfo

For AT&T accounts you'll have to create a secure mail key. This is like an app password, but it isn't a passkey though. https://www.att.com/support/article/email-support/KM1240308/

Also, 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.

Hi Chris-- I used manual configuration to create the account in Thunderbird. My husband uses Thunderbird (on his Windows11 desktop) and I copied his setting exactly. Except, when I entered my password, I tried both my regular password that I use to access my email in Yahoo Mail, and the passkey that I created last February. I created the passkey because I got a message from Mozilla saying I need to. I had created the passkey in Yahoo.com, but now when I log into Yahoo, the link to the passkey page isn't on my Profile page where it is supposed to be. I think this may be because my email address is a prodigy.net address, which is managed by at&t (in Yahoo Mail). When I go to Yahoo.com, my security page DOES NOT INCLUDE a link to "Create a passkey." When I go to at&t, my profile page does not include a link to "Create a secure mail key. If any of this makes sense to you, a thousand thank you's, Deb Fisher

Here is the Troubleshooting info: Application Basics Name Thunderbird Version 159.0 Build ID 20261026161902 Distribution ID Update Channel release User Agent Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:159.0) Gecko/20100101 Thunderbird/159.0 OS Windows_NT 10.0 19045 OS Theme Launcher Process Enabled Multiprocess Windows 0/0 Fission Windows 0/0 Enabled by default Remote Processes 3

Enterprise Policies Inactive Google Location Service Key Found Google Safebrowsing Key Missing Mozilla Location Service Key Missing Safe Mode true Memory Size (RAM) 7.9 GB Disk Space Available 317 GB Mail and News Accounts ID Incoming server Outgoing servers Name Connection security Authentication method Name Connection security Authentication method Default? account2 (none) Local Folders 0 3 Libraries Library Status Expected minimum version Version in use Path RNP (OpenPGP) OK 0.18.1 0.18.1.MZLA.159.0.botan.3.11.1 C:\Program Files\Mozilla Thunderbird\rnp.dll OTR Failed to load. OTR chat encryption will not work. - - - Calendar Settings Home Name Value Name Type storage Disabled Username URI Refresh Interval Read-only Suppress Alarms Cache Enabled iMIP Identity iMIP Disabled iMIP Account Organizer Id Force Email Scheduling Popup Alarms Supported Alarms on Invitation Supported Max Alarms Per Event Attachment Supported Max Categories Privacy State Supported Priority Supported true Event Supported Task Supported Local Time Supported UTC/GMT Supported Auto-Scheduling Supported Home Name Value Name Type storage Disabled true Username URI Refresh Interval Read-only Suppress Alarms Cache Enabled iMIP Identity iMIP Disabled iMIP Account Organizer Id Force Email Scheduling Popup Alarms Supported Alarms on Invitation Supported Max Alarms Per Event Attachment Supported Max Categories Privacy State Supported Priority Supported true Event Supported Task Supported Local Time Supported UTC/GMT Supported Auto-Scheduling Supported

Crash Reports for the Last 3 Days Report ID Submitted Remote Processes Type Count GPU 1 Extension 1 RDD 1 Add-ons Name Type Version Enabled Location ID Thundermail extension 2.0.16 true app-builtin-addons tbpro-system-add-on@thunderbird.net System theme — auto theme 1.4.2 true app-builtin default-theme@mozilla.org Dark theme 1.3.2 false app-builtin thunderbird-compact-dark@mozilla.org Light theme 1.3.2 false app-builtin thunderbird-compact-light@mozilla.org Security Software Type Name Antivirus Microsoft Defender Antivirus Antispyware Firewall Windows Firewall Legacy User Stylesheets Active false Stylesheets No stylesheets found Graphics Features Compositing WebRender (Software) Font Visibility Debug Info Windows Platform Asynchronous Pan/Zoom wheel input enabled; scrollbar drag enabled; keyboard enabled; autoscroll enabled; smooth pinch-zoom enabled WebGL 1 Driver WSI Info EGL_VENDOR: Google Inc. (Intel) EGL_VERSION: 1.5 (ANGLE 2.1 git hash: unknown hash) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_display_semaphore_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_ANGLE_image_d3d11_texture EGL_ANGLE_create_context_backwards_compatible EGL_KHR_no_config_context EGL_KHR_create_context_no_error EGL_KHR_reusable_sync EGL_ANGLE_memory_usage_report EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_device_query EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_platform_angle_d3d11on12 EGL_ANGLE_platform_angle_d3d_luid EGL_ANGLE_platform_angle_device_id EGL_ANGLE_platform_angle_display_key EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_feature_control EGL_ANGLE_no_error WebGL 1 Driver Renderer Google Inc. (Intel) -- ANGLE (Intel, Intel(R) HD Graphics 4600 (0x00000412) Direct3D11 vs_5_0 ps_5_0, D3D11-20.19.15.5126) WebGL 1 Driver Version OpenGL ES 3.0 (ANGLE 2.1 git hash: unknown hash) WebGL 1 Driver Extensions GL_AMD_performance_monitor GL_ANGLE_base_vertex_base_instance_shader_builtin GL_ANGLE_blob_cache GL_ANGLE_client_arrays GL_ANGLE_clip_cull_distance GL_ANGLE_copy_texture_3d GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_get_serialized_context_string GL_ANGLE_get_tex_level_parameter GL_ANGLE_instanced_arrays GL_ANGLE_memory_size GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_polygon_mode GL_ANGLE_program_binary_readiness_query GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_renderability_validation GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_shader_pixel_local_storage GL_ANGLE_shader_pixel_local_storage_coherent GL_ANGLE_stencil_texturing GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_multisample GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_APPLE_clip_distance GL_ARM_rgba8 GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_lose_context GL_EXT_EGL_image_external_wrap_modes GL_EXT_base_instance GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_clip_control GL_EXT_clip_cull_distance GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_conservative_depth GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_depth_clamp GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_polygon_offset_clamp GL_EXT_read_format_bgra GL_EXT_render_snorm GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_border_clamp GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_mirror_clamp_to_edge GL_EXT_texture_norm16 GL_EXT_texture_rg GL_EXT_texture_storage GL_EXT_texture_type_2_10_10_10_REV GL_EXT_unpack_subimage GL_KHR_debug GL_KHR_parallel_shader_compile GL_KHR_robust_buffer_access_behavior GL_KHR_robustness GL_NV_EGL_stream_consumer_external GL_NV_fence GL_NV_framebuffer_blit GL_NV_pack_subimage GL_NV_pixel_buffer_object GL_NV_shader_noperspective_interpolation GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_image_external_essl3 GL_OES_depth24 GL_OES_depth32 GL_OES_draw_buffers_indexed GL_OES_draw_elements_base_vertex GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_required_internalformat GL_OES_rgb8_rgba8 GL_OES_sample_variables GL_OES_shader_multisample_interpolation GL_OES_standard_derivatives GL_OES_surfaceless_context GL_OES_texture_border_clamp GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_texture_stencil8 GL_OES_texture_storage_multisample_2d_array GL_OES_vertex_array_object GL_OVR_multiview GL_OVR_multiview2 WebGL 1 Extensions ANGLE_instanced_arrays EXT_blend_minmax EXT_clip_control EXT_color_buffer_half_float EXT_depth_clamp EXT_float_blend EXT_frag_depth EXT_polygon_offset_clamp EXT_shader_texture_lod EXT_sRGB

Hi Chris--

    I used manual configuration to create the account in Thunderbird. My husband uses Thunderbird (on his Windows11 desktop) and I copied his setting exactly. Except, when I entered my password, I tried both my regular password that I use to access my email in Yahoo Mail, and the passkey that I created last February. I created the passkey because I got a message from Mozilla saying I need to.
    I had created the passkey in Yahoo.com, but now when I log into Yahoo, the link to the passkey page isn't on my Profile page where it is supposed to be. I think this may be because my email address is a prodigy.net address, which is managed by at&t (in Yahoo Mail). When I go to Yahoo.com, my security page DOES NOT INCLUDE a link to "Create a passkey." When I go to at&t, my profile page does not include a link to "Create a secure mail key. 

Here is the Troubleshooting info: Application Basics Name Thunderbird Version 159.0 Build ID 20261026161902 Distribution ID Update Channel release User Agent Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:159.0) Gecko/20100101 Thunderbird/159.0 OS Windows_NT 10.0 19045 OS Theme Launcher Process Enabled Multiprocess Windows 0/0 Fission Windows 0/0 Enabled by default Remote Processes 3

Enterprise Policies Inactive Google Location Service Key Found Google Safebrowsing Key Missing Mozilla Location Service Key Missing Safe Mode true Memory Size (RAM) 7.9 GB Disk Space Available 317 GB Mail and News Accounts ID Incoming server Outgoing servers Name Connection security Authentication method Name Connection security Authentication method Default? account2 (none) Local Folders 0 3 Libraries Library Status Expected minimum version Version in use Path RNP (OpenPGP) OK 0.18.1 0.18.1.MZLA.159.0.botan.3.11.1 C:\Program Files\Mozilla Thunderbird\rnp.dll OTR Failed to load. OTR chat encryption will not work. - - - Calendar Settings Home Name Value Name Type storage Disabled Username URI Refresh Interval Read-only Suppress Alarms Cache Enabled iMIP Identity iMIP Disabled iMIP Account Organizer Id Force Email Scheduling Popup Alarms Supported Alarms on Invitation Supported Max Alarms Per Event Attachment Supported Max Categories Privacy State Supported Priority Supported true Event Supported Task Supported Local Time Supported UTC/GMT Supported Auto-Scheduling Supported Home Name Value Name Type storage Disabled true Username URI Refresh Interval Read-only Suppress Alarms Cache Enabled iMIP Identity iMIP Disabled iMIP Account Organizer Id Force Email Scheduling Popup Alarms Supported Alarms on Invitation Supported Max Alarms Per Event Attachment Supported Max Categories Privacy State Supported Priority Supported true Event Supported Task Supported Local Time Supported UTC/GMT Supported Auto-Scheduling Supported

Crash Reports for the Last 3 Days Report ID Submitted Remote Processes Type Count GPU 1 Extension 1 RDD 1 Add-ons Name Type Version Enabled Location ID Thundermail extension 2.0.16 true app-builtin-addons tbpro-system-add-on@thunderbird.net System theme — auto theme 1.4.2 true app-builtin default-theme@mozilla.org Dark theme 1.3.2 false app-builtin thunderbird-compact-dark@mozilla.org Light theme 1.3.2 false app-builtin thunderbird-compact-light@mozilla.org Security Software Type Name Antivirus Microsoft Defender Antivirus Antispyware Firewall Windows Firewall Legacy User Stylesheets Active false Stylesheets No stylesheets found Graphics Features Compositing WebRender (Software) Font Visibility Debug Info Windows Platform Asynchronous Pan/Zoom wheel input enabled; scrollbar drag enabled; keyboard enabled; autoscroll enabled; smooth pinch-zoom enabled WebGL 1 Driver WSI Info EGL_VENDOR: Google Inc. (Intel) EGL_VERSION: 1.5 (ANGLE 2.1 git hash: unknown hash) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_display_semaphore_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_ANGLE_image_d3d11_texture EGL_ANGLE_create_context_backwards_compatible EGL_KHR_no_config_context EGL_KHR_create_context_no_error EGL_KHR_reusable_sync EGL_ANGLE_memory_usage_report EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_device_query EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_platform_angle_d3d11on12 EGL_ANGLE_platform_angle_d3d_luid EGL_ANGLE_platform_angle_device_id EGL_ANGLE_platform_angle_display_key EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_feature_control EGL_ANGLE_no_error WebGL 1 Driver Renderer Google Inc. (Intel) -- ANGLE (Intel, Intel(R) HD Graphics 4600 (0x00000412) Direct3D11 vs_5_0 ps_5_0, D3D11-20.19.15.5126) WebGL 1 Driver Version OpenGL ES 3.0 (ANGLE 2.1 git hash: unknown hash) WebGL 1 Driver Extensions GL_AMD_performance_monitor GL_ANGLE_base_vertex_base_instance_shader_builtin GL_ANGLE_blob_cache GL_ANGLE_client_arrays GL_ANGLE_clip_cull_distance GL_ANGLE_copy_texture_3d GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_get_serialized_context_string GL_ANGLE_get_tex_level_parameter GL_ANGLE_instanced_arrays GL_ANGLE_memory_size GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_polygon_mode GL_ANGLE_program_binary_readiness_query GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_renderability_validation GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_shader_pixel_local_storage GL_ANGLE_shader_pixel_local_storage_coherent GL_ANGLE_stencil_texturing GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_multisample GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_APPLE_clip_distance GL_ARM_rgba8 GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_lose_context GL_EXT_EGL_image_external_wrap_modes GL_EXT_base_instance GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_clip_control GL_EXT_clip_cull_distance GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_conservative_depth GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_depth_clamp GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_polygon_offset_clamp GL_EXT_read_format_bgra GL_EXT_render_snorm GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_border_clamp GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_mirror_clamp_to_edge GL_EXT_texture_norm16 GL_EXT_texture_rg GL_EXT_texture_storage GL_EXT_texture_type_2_10_10_10_REV GL_EXT_unpack_subimage GL_KHR_debug GL_KHR_parallel_shader_compile GL_KHR_robust_buffer_access_behavior GL_KHR_robustness GL_NV_EGL_stream_consumer_external GL_NV_fence GL_NV_framebuffer_blit GL_NV_pack_subimage GL_NV_pixel_buffer_object GL_NV_shader_noperspective_interpolation GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_image_external_essl3 GL_OES_depth24 GL_OES_depth32 GL_OES_draw_buffers_indexed GL_OES_draw_elements_base_vertex GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_required_internalformat GL_OES_rgb8_rgba8 GL_OES_sample_variables GL_OES_shader_multisample_interpolation GL_OES_standard_derivatives GL_OES_surfaceless_context GL_OES_texture_border_clamp GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_texture_stencil8 GL_OES_texture_storage_multisample_2d_array GL_OES_vertex_array_object GL_OVR_multiview GL_OVR_multiview2 WebGL 1 Extensions ANGLE_instanced_arrays EXT_blend_minmax EXT_clip_control EXT_color_buffer_half_float EXT_depth_clamp EXT_float_blend EXT_frag_depth EXT_polygon_offset_clamp EXT_shader_texture_lod EXT_sRGB WEBGL_compressed_texture_s3tc_srgb WEBGL_debug_renderer_info WEBGL_debug_shaders WEBGL_depth_texture [cut off to meet space limit]

Hi Chris--

   I used manual configuration to create the account in Thunderbird. My husband uses Thunderbird (on his Windows11 desktop) and I copied his setting exactly. Except, when I entered my password, I tried both my regular password that I use to access my email in Yahoo Mail, and the passkey that I created last February. I created the passkey because I got a message from Mozilla saying I need to.
   I had created the passkey in Yahoo.com, but now when I log into Yahoo, the link to the passkey page isn't on my Profile page where it is supposed to be. I think this may be because my email address is a prodigy.net address, which is managed by at&t (in Yahoo Mail). When I go to Yahoo.com, my security page DOES NOT INCLUDE a link to "Create a passkey." When I go to at&t, my profile page does not include a link to "Create a secure mail key. 
    Troubleshooting info to follow.

Thank you.

Troubleshooting Info Application Basics Name Thunderbird Version 159.0 Build ID 20261026161902 Distribution ID Update Channel release User Agent Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:159.0) Gecko/20100101 Thunderbird/159.0 OS Windows_NT 10.0 19045 OS Theme Launcher Process Enabled Multiprocess Windows 0/0 Fission Windows 0/0 Enabled by default Remote Processes 3

Enterprise Policies Inactive Google Location Service Key Found Google Safebrowsing Key Missing Mozilla Location Service Key Missing Safe Mode true Memory Size (RAM) 7.9 GB Disk Space Available 317 GB WebGL 1 Extensions ANGLE_instanced_arrays EXT_blend_minmax EXT_clip_control EXT_color_buffer_half_float EXT_depth_clamp EXT_float_blend EXT_frag_depth EXT_polygon_offset_clamp EXT_shader_texture_lod EXT_sRGB EXT_texture_compression_bptc EXT_texture_compression_rgtc EXT_texture_filter_anisotropic EXT_texture_mirror_clamp_to_edge MOZ_debug OES_element_index_uint OES_fbo_render_mipmap OES_standard_derivatives OES_texture_float OES_texture_float_linear OES_texture_half_float OES_texture_half_float_linear OES_vertex_array_object WEBGL_color_buffer_float WEBGL_compressed_texture_s3tc WEBGL_compressed_texture_s3tc_srgb WEBGL_debug_renderer_info WEBGL_debug_shaders WEBGL_depth_texture WEBGL_draw_buffers WEBGL_lose_context WEBGL_provoking_vertex WebGL 2 Driver WSI Info EGL_VENDOR: Google Inc. (Intel) EGL_VERSION: 1.5 (ANGLE 2.1 git hash: unknown hash) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_display_semaphore_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_ANGLE_image_d3d11_texture EGL_ANGLE_create_context_backwards_compatible EGL_KHR_no_config_context EGL_KHR_create_context_no_error EGL_KHR_reusable_sync EGL_ANGLE_memory_usage_report EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_device_query EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_platform_angle_d3d11on12 EGL_ANGLE_platform_angle_d3d_luid EGL_ANGLE_platform_angle_device_id EGL_ANGLE_platform_angle_display_key EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_feature_control EGL_ANGLE_no_error WebGL 2 Driver Renderer Google Inc. (Intel) -- ANGLE (Intel, Intel(R) HD Graphics 4600 (0x00000412) Direct3D11 vs_5_0 ps_5_0, D3D11-20.19.15.5126) WebGL 2 Driver Version OpenGL ES 3.0 (ANGLE 2.1 git hash: unknown hash) WebGL 2 Driver Extensions GL_AMD_performance_monitor GL_ANGLE_base_vertex_base_instance_shader_builtin GL_ANGLE_blob_cache GL_ANGLE_client_arrays GL_ANGLE_clip_cull_distance GL_ANGLE_copy_texture_3d GL_ANGLE_depth_texture GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_get_serialized_context_string GL_ANGLE_get_tex_level_parameter GL_ANGLE_instanced_arrays GL_ANGLE_memory_size GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_polygon_mode GL_ANGLE_program_binary_readiness_query GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_renderability_validation GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_shader_pixel_local_storage GL_ANGLE_shader_pixel_local_storage_coherent GL_ANGLE_stencil_texturing GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_multisample GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_APPLE_clip_distance GL_ARM_rgba8 GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_lose_context GL_EXT_EGL_image_external_wrap_modes GL_EXT_base_instance GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_clip_control GL_EXT_clip_cull_distance GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_conservative_depth GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_depth_clamp GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_polygon_offset_clamp GL_EXT_read_format_bgra GL_EXT_render_snorm GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_border_clamp GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_mirror_clamp_to_edge GL_EXT_texture_norm16 GL_EXT_texture_rg GL_EXT_texture_storage GL_EXT_texture_type_2_10_10_10_REV GL_EXT_unpack_subimage GL_KHR_debug GL_KHR_parallel_shader_compile GL_KHR_robust_buffer_access_behavior GL_KHR_robustness GL_NV_EGL_stream_consumer_external GL_NV_fence GL_NV_framebuffer_blit GL_NV_pack_subimage GL_NV_pixel_buffer_object GL_NV_shader_noperspective_interpolation GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_image_external_essl3 GL_OES_depth24 GL_OES_depth32 GL_OES_draw_buffers_indexed GL_OES_draw_elements_base_vertex GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_required_internalformat GL_OES_rgb8_rgba8 GL_OES_sample_variables GL_OES_shader_multisample_interpolation GL_OES_standard_derivatives GL_OES_surfaceless_context GL_OES_texture_border_clamp GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_texture_stencil8 GL_OES_texture_storage_multisample_2d_array GL_OES_vertex_array_object GL_OVR_multiview GL_OVR_multiview2 WebGL 2 Extensions EXT_clip_control EXT_color_buffer_float EXT_depth_clamp EXT_float_blend EXT_polygon_offset_clamp EXT_texture_compression_bptc EXT_texture_compression_rgtc EXT_texture_filter_anisotropic EXT_texture_mirror_clamp_to_edge EXT_texture_norm16 MOZ_debug OES_draw_buffers_indexed OES_texture_float_linear OVR_multiview2 WEBGL_compressed_texture_s3tc WEBGL_compressed_texture_s3tc_srgb WEBGL_debug_renderer_info WEBGL_debug_shaders WEBGL_lose_context WEBGL_provoking_vertex Target Frame Rate 60 DirectWrite true (10.0.19041.1566) GPU #1 Active Yes Description Intel(R) HD Graphics 4600 Vendor ID 0x8086 Device ID 0x0412 Driver Version 20.19.15.5126 Driver Date 1-21-2020 Drivers igdumdim64 igd10iumd64 igd10iumd64 igd12umd64 igdumdim32 igd10iumd32 igd10iumd32 igd12umd32 Subsys ID 1998103c RAM 0 GPU #2 Active No Description Trigger 6 External Graphics Vendor ID 0x000b Device ID 0x000b Driver Version 1.9.2501.423 Driver Date 4-23-2025 Drivers Unknown Subsys ID 0000000b RAM 0 Diagnostics AzureCanvasBackend skia AzureCanvasBackend (UI Process) skia AzureContentBackend skia AzureContentBackend (UI Process) skia AzureFallbackCanvasBackend (UI Process) skia

As per your Troubleshooting Information, no AT&T account exists in your Thunderbird profile. So I have no idea what server settings you tried and how this is related to Yahoo.

See https://www.att.com/support/article/email-support/KM1010523/ for more information.

As stated before, AT&T require a secure mail key. https://www.att.com/support/article/email-support/KM1240308/