Cannot retrieve IMAP mail from Gmail using Thunderbird
My overall goal is to switch over from POP3 to IMAP without losing my previous messages. So I just created in Thunderbird an IMAP version of my POP3 Gmail account. I have been led to believe this is permitted and, clearly I don't want to wipe out my POP3 account (and all of its messages on my local system) until I know the IMAP works. So now I have two "accounts" defined in Thunderbird with the same email address: one is pointing to Gmail POP3 and one to Gmail IMAP. Now, any attempt to retrieve mail from IMAP results in the error "the mail server for account <xxxx>@gmail.com responded : Unknown command <gibberish string>". (See error image attached.) The gibberish string is different each time I try it.
I have enabled IMAP in my Gmail account config.
I have searched the web for similar problems and none of the proposed solutions work for me.
Other data: using latest Thunderbird on Windows 10. Any clues?
My overall goal is to switch over from POP3 to IMAP without losing my previous messages. So I just created in Thunderbird an IMAP version of my POP3 Gmail account. I have been led to believe this is permitted and, clearly I don't want to wipe out my POP3 account (and all of its messages on my local system) until I know the IMAP works. So now I have two "accounts" defined in Thunderbird with the same email address: one is pointing to Gmail POP3 and one to Gmail IMAP. Now, any attempt to retrieve mail from IMAP results in the error "the mail server for account <xxxx>@gmail.com responded : Unknown command <gibberish string>". (See error image attached.) The gibberish string is different each time I try it.
I have enabled IMAP in my Gmail account config.
I have searched the web for similar problems and none of the proposed solutions work for me.
Other data: using latest Thunderbird on Windows 10. Any clues?
Wšykne wótegrona (4)
Looks like the image didn't make it into my question. I'll try again.
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 (truncated to 10k characters):
Application Basics
Name: Thunderbird Version: 52.4.0 User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 Profile Folder: Open Folder
(Local drive) Application Build ID: 20171004092449 Enabled Plugins: about:plugins Build Configuration: about:buildconfig Memory Use: about:memory Profiles: about:profiles
Mail and News Accounts
account1:
INCOMING: account1, , (none) Local Folders, plain, passwordCleartext
account4:
INCOMING: account4, , (pop3) pop.gmail.com:995, SSL, passwordCleartext
OUTGOING: , smtp.gmail.com:465, SSL, passwordCleartext, true
OUTGOING: , smtp.gmail.com:465, SSL, passwordCleartext, false
OUTGOING: , smtp.gmail.com:465, SSL, passwordCleartext, false
account6:
INCOMING: account6, , (pop3) pop.gmail.com:995, SSL, passwordCleartext
OUTGOING: , smtp.gmail.com:465, SSL, passwordCleartext, true
account9:
INCOMING: account9, , (imap) imap.gmail.com:993, SSL, OAuth2
OUTGOING: , smtp.gmail.com:465, SSL, passwordCleartext, true
Crash Reports https://crash-stats.mozilla.com/report/index/bp-5069e4b7-b971-4116-9149-baf170170722 (22/07/2017) https://crash-stats.mozilla.com/report/index/bp-34337d76-53a1-4b53-a63a-6c60f2170110 (11/01/2017) https://crash-stats.mozilla.com/report/index/bp-ab433662-db4c-42c4-be31-473fd2170110 (11/01/2017) https://crash-stats.mozilla.com/report/index/bp-63b73de2-4ad3-400d-ab13-96db12140726 (27/07/2014)
Extensions
gContactSync, 2.0.12, true, gContactSync@pirules.net
Google Search for Thunderbird, 1.0, true, gsearch@standard8.plus.com
ImportExportTools, 3.2.4.1, true, {3ed8cc52-86fc-4613-9026-c1ef969da4c3}
Lightning, 5.4.4, 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
dom.apps.reset-permissions: true
extensions.lastAppVersion: 52.4.0
font.internaluseonly.changed: true
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.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.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.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: 14
gfx.crash-guard.glcontext.appVersion: 45.4.0
gfx.crash-guard.glcontext.deviceID: 0x11c0
gfx.crash-guard.glcontext.driverVersion: 21.21.13.7306
gfx.crash-guard.glcontext.gfx.driver-init.direct3d11-angle: true
gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle: true
gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-d3d11: false
gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-warp: false
gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-try-d3d11: true
gfx.crash-guard.status.glcontext: 2
gfx.direct3d.last_used_feature_level_idx: 0
mail.openMessageBehavior.version: 1
mail.winsearch.enable: true
mail.winsearch.firstRunDone: true
mail.winsearch.global_reindex_time: 1261614790
mailnews.database.global.datastore.id: ab70c48f-e248-4462-95e0-92db516b008
media.gmp.storage.version.observed: 1
network.cookie.prefsMigrated: true
network.predictor.cleaned-up: true
places.database.lastMaintenance: 1509079733
places.history.expiration.transient_current_max_pages: 54011
plugin.importedState: true
plugins.update.notifyUser: true
print.print_printer: Canon iP4500 series
print.printer_Canon_Inkjet_iP4500_series.print_bgcolor: false
print.printer_Canon_Inkjet_iP4500_series.print_bgimages: false
print.printer_Canon_Inkjet_iP4500_series.print_command:
print.printer_Canon_Inkjet_iP4500_series.print_downloadfonts: false
print.printer_Canon_Inkjet_iP4500_series.print_edge_bottom: 0
print.printer_Canon_Inkjet_iP4500_series.print_edge_left: 0
print.printer_Canon_Inkjet_iP4500_series.print_edge_right: 0
print.printer_Canon_Inkjet_iP4500_series.print_edge_top: 0
print.printer_Canon_Inkjet_iP4500_series.print_evenpages: true
print.printer_Canon_Inkjet_iP4500_series.print_footercenter:
print.printer_Canon_Inkjet_iP4500_series.print_footerleft: &PT
print.printer_Canon_Inkjet_iP4500_series.print_footerright: &D
print.printer_Canon_Inkjet_iP4500_series.print_headercenter:
print.printer_Canon_Inkjet_iP4500_series.print_headerleft: &T
print.printer_Canon_Inkjet_iP4500_series.print_headerright: &U
print.printer_Canon_Inkjet_iP4500_series.print_in_color: true
print.printer_Canon_Inkjet_iP4500_series.print_margin_bottom: 0.5
print.printer_Canon_Inkjet_iP4500_series.print_margin_left: 0.5
print.printer_Canon_Inkjet_iP4500_series.print_margin_right: 0.5
print.printer_Canon_Inkjet_iP4500_series.print_margin_top: 0.5
print.printer_Canon_Inkjet_iP4500_series.print_oddpages: true
print.printer_Canon_Inkjet_iP4500_series.print_orientation: 0
print.printer_Canon_Inkjet_iP4500_series.print_pagedelay: 500
print.printer_Canon_Inkjet_iP4500_series.print_paper_data: 9
print.printer_Canon_Inkjet_iP4500_series.print_paper_height: 11.00
print.printer_Canon_Inkjet_iP4500_series.print_paper_size_type: 0
print.printer_Canon_Inkjet_iP4500_series.print_paper_size_unit: 1
print.printer_Canon_Inkjet_iP4500_series.print_paper_width: 8.50
print.printer_Canon_Inkjet_iP4500_series.print_reversed: false
print.printer_Canon_Inkjet_iP4500_series.print_scaling: 1.00
print.printer_Canon_Inkjet_iP4500_series.print_shrink_to_fit: true
print.printer_Canon_Inkjet_iP4500_series.print_to_file: false
print.printer_Canon_Inkjet_iP4500_series.print_unwriteable_margin_bottom: 0
print.printer_Canon_Inkjet_iP4500_series.print_unwriteable_margin_left: 0
print.printer_Canon_Inkjet_iP4500_series.print_unwriteable_margin_right: 0
print.printer_Canon_Inkjet_iP4500_series.print_unwriteable_margin_top: 0
print.printer_Canon_iP4500_series.print_bgcolor: false
print.printer_Canon_iP4500_series.print_bgimages: false
print.printer_Canon_iP4500_series.print_colorspace:
print.printer_Canon_iP4500_series.print_command:
print.printer_Canon_iP4500_series.print_downloadfonts: false
print.printer_Canon_iP4500_series.print_duplex: 0
print.printer_Canon_iP4500_series.print_edge_bottom: 0
print.printer_Canon_iP4500_series.print_edge_left: 0
print.printer_Canon_iP4500_series.print_edge_right: 0
print.printer_Canon_iP4500_series.print_edge_top: 0
print.printer_Canon_iP4500_series.print_evenpages: true
print.printer_Canon_iP4500_series.print_footercenter:
print.printer_Canon_iP4500_series.print_footerleft: &PT
print.printer_Canon_iP4500_series.print_footerright: &D
print.printer_Canon_iP4500_series.print_headercenter:
print.printer_Canon_iP4500_series.print_headerleft: &T
print.printer_Canon_iP4500_series.print_headerright: &U
print.printer_Canon_iP4500_series.print_in_color: true
print.printer_Canon_iP4500_series.print_margin_bottom: 0.5
print.printer_Canon_iP4500_series.print_margin_left: 0.5
print.printer_Canon_iP4500_series.print_margin_right: 0.5
print.printer_Canon_iP4500_series.print_margin_top: 0.5
print.printer_Canon_iP4500_series.print_oddpages: true
print.printer_Canon_iP4500_series.print_orientation: 0
print.printer_Canon_iP4500_series.print_page_delay: 50
print.printer_Canon_iP4500_series.print_pagedelay: 500
print.printer_Canon_iP4500_series.print_paper_data: 9
print.printer_Canon_iP4500_series.print_paper_height: 11.00
print.printer_Canon_iP4500_series.print_paper_name:
print.printer_Canon_iP4500_series.print_paper_size_type: 0
print.printer_Canon_iP4500_series.print_paper_size_unit: 1
print.printer_Canon_iP4500_series.print_paper_width: 8.50
print.printer_Canon_iP4500_series.print_plex_name:
print.printer_Canon_iP4500_series.print_resolution: 0
print.printer_Canon_iP4500_series.print_resolution_name:
print.printer_Canon_iP4500_series.print_reversed: false
print.printer_Canon_iP4500_series.print_scaling: 0.80
print.printer_Canon_iP4500_series.print_shrink_to_fit: false
print.printer_Canon_iP4500_series.print_to_file: false
...
Your Gmail IMAP server settings look good. I'd also set the 'Authentication type' for the Gmail SMTP server to 'OAuth2'.
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?