Please post here your Troubleshooting Information from Thunderbird: Thunderbird menu: Help: Troubleshooting Information Click the "Copy text to clipboard" button. Paste (Ctrl-V), the text into your response here.

Application Basics

   Name: Thunderbird
   Version: 45.6.0
   User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0
   Profile Directory: Open Directory

             (Local drive)
   Application Build ID: 20170106114713
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (imap) imapmail.libero.it:143, plain, passwordEncrypted
     OUTGOING: , smtp.libero.it:587, alwaysSTARTTLS, passwordEncrypted, true

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

   account3:
     INCOMING: account3, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

   account4:
     INCOMING: account4, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

   account5:
     INCOMING: account5, , (pop3) pop3s.aruba.it:110, plain, passwordCleartext
     OUTGOING: , smtps.aruba.it:465, SSL, passwordCleartext, true

   account6:
     INCOMING: account6, , (imap) mail.di.unipmn.it:993, SSL, passwordCleartext
     OUTGOING: , mail.di.unipmn.it:465, SSL, passwordCleartext, true

 Crash Reports

 Extensions
   Lightning, 4.7.6, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}
   Provider for Google Calendar, 3.1, true, {a62ef8ec-5fdc-40c2-873c-223b8a6925cc}

 Important Modified Preferences

   Name: Value

     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.crash-guard.glcontext.appVersion: 45.6.0
     gfx.crash-guard.glcontext.deviceID: Mesa DRI Intel(R) HD Graphics 620 (Kabylake GT2)
     gfx.crash-guard.glcontext.driverVersion: 3.0 Mesa 13.0.3
     gfx.crash-guard.status.glcontext: 1
     mail.openMessageBehavior.version: 1
     mailnews.database.global.datastore.id: bb0a6f59-3d7a-40f3-a45e-966effa9b09
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1484580491
     places.history.expiration.transient_current_max_pages: 104858
     plugin.importedState: true

 Graphics

     Adapter Description: Intel Open Source Technology Center -- Mesa DRI Intel(R) HD Graphics 620 (Kabylake GT2)
     Vendor ID: Intel Open Source Technology Center
     Device ID: Mesa DRI Intel(R) HD Graphics 620 (Kabylake GT2)
     Driver Version: 3.0 Mesa 13.0.3
     WebGL Renderer: false

     AzureCanvasBackend: cairo
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: none
     AzureContentBackend: cairo
     CairoUseXRender: 1

 JavaScript

 Incremental GC:

 Accessibility

   Activated:
   Prevent Accessibility:

 Library Versions

I see that you have IMAP accounts for libero.it, unipmn.it, and two for Gmail. Which one is having the problem?

I see that your settings for libero.it are not the ones that Libero says they should be, namely the port numbers and using SSL: http://aiuto.libero.it/articolo/mail/parametri-di-configurazione-per-il-client-di-posta/

IMAP: – Server: imapmail.libero.it – Porta: 993 con SSL SMTP (con SSL): – Server: smtp.libero.it (selezionando la richiesta di autenticazione) – Porta: 465 con SSL

They even have a tutorial for how to set up Thunderbird (link at the bottom of their page).

Thank you Bruce for your reply. This is exactly the point. I have used the setting suggested by libero.it for days with no luck, then I decide to set as "autodetect" those parameters and then magically I was able to download the email. If I change it with the suggested parameters I got the problem mentioned in the subject.

What is weird to me is that problem is only on the last thunderbird. I used a previous version of thunderbid in my previous laptop and no problem. Even the client on my android (aquamail) phone are able to accept the suggested parameters. Thunderbird is the only one with this problem.

Thanks, Massimo

That's strange. When I let Thunderbird "autodetect" the settings for Libero.it, I get the exact settings they recommend, namely IMAP port 993, SSL/TLS and normal password. Not the settings you have, which is IMAP port 143, no SSL, and encrypted password.

See my screenshot.

Please goto help > troubleshooting information.

Is your account with liberto.it showing a connection security of none?

According to the troubleshooting information he gave: INCOMING: account1, , (imap) imapmail.libero.it:143, plain, passwordEncrypted

Perhaps that has changed now.

Well guys, No idea what happens but after few days working with the "no-ssl" settings, I tried to set the SSL "on" and it starts working.

Maybe is something related to my connection, but I'm not sure.

Anyway, thanks for your time.

Best, Massimo