You have added an email account in Thunderbird after giving your login credentials, like email address and password. But you have noticed that there is a trouble signing in, either immediately or after a few days of being able to use it normally.
Email Account In Thunderbird (Fix & Settings)
This post will help you understand and correct, if needed, the server settings of an email account that you added to Thunderbird.
When you first add an email account, like IMAP based accounts, Thunderbird only asks for your name, email address (like [email protected]) and the password you use to login to this. If you are NOT adding an account of any emailing service that is not likely in Thunderbird’s database, you do not need to do anything else. Otherwise, other details are also needed.
It is likely that you were able to use your account in Thunderbird and being able to fetch/download emails fine for a few days, but then it suddenly started experiencing problems. It often happens due to some changes from your email providers’ side. Whatever the reason is, you can read below to understand what all settings you can change to fix your problems.
The Settings
First, go to “Settings” from the right-side on the top (click this icon ≡). Then click on ‘Options’ ->‘Account Settings.’ This will open up the settings dialog box for the account that you were using in Thunderbird at that time, as shown below in the image.

The most important category is that of ‘Server Settings,’ which is often the cause of the problems you face while signing in or with other downloading/synchronization problems.

Check with your email provider for these details and then correct them here. They might have also changed it, so you need to update them all here.
- Server name
- The user name you sign in with
- The port numbers
- Connection security type
- Authentication type used by the email provider
Also note, if you have turned on the two-step authentication for your email account (like when an OTP is sent on your phone), you might need to get an additional “App Password” from your provider that you need to enter in Thunderbird for it to work.
Other settings that can also affect the functioning of Thunderbird with your email account are:
- See if “check for new messages” is set for a very long duration. You can set it to check every 10 or 5 minutes or so. Whatever you find comfortable with your internet connection.
- Also check directory of your Thunderbird Profiles and if that directory has any corruption issues. It will be by default under “USER\AppData\Roaming\Thunderbird\Profiles.”
- Check under “Synchronization and Storage” category if the “synchronize the most recent” is set to very few days. If that’s the case, Thunderbird will not download any older messages than the specified period. If you need to fetch all the emails regardless if they are recent or very old, check the setting that says, “Synchronize all messages locally regardless of age.” This will get all the messages from the very first time you created your email account.
- Also check if the setting “don’t downloaded messages larger than” is turned on. If it is, Thunderbird will only download the headers of those emails larger than the specified size, but you won’t be able to see the content. Only turn it on if you have the space problem with your computer.
- Under the “Synchronization & Storage” -> Disk Space, check if “Don’t delete any messages” is checked. If you cannot find the older messages, it might be that the “deleting” options are turned on (like delete all but recent or delete older messages).
And finally, enter your login ID and password once again, carefully, to resolve one of the very common and the most annoying problems people face while setting up an email account in email clients. This happens usually when they change their password but forget to update it in Thunderbird. Check if that applies to you as well.