See if this is being caused by an email with a date that is much older than expected. Maybe a date and time before the account was set up. In Inbox look at the last email you successfully download . Note the Subject and Date as you may need this info later. Move all emails out of the Inbox into other suitable folders and then right click on folder and select 'compact'. You should now have a clean and empty Inbox. Try to 'Get Messages' If you get error then maybe the problem email is stuck on the server causing a blockage. check the following: Logon to the webmail account via a browser. Empty the Junk/Spam folder Look in Inbox for the last email successfully downloaded to Thunderbird mail account Inbox. Then read next email - check it's date - if not required then delete it or move it out of the Inbox into another folder. Then retry to Get Message in Thunderbird.