Thunderbird Inbox Full cannot Receive Email! – [SOLVED 2026]

As a Thunderbird user, one will face many errors within Thunderbird mailbox. One of the common issues is the incapability to access emails in the inbox. In case you are searching for a friendly and effective way out to fix the issue “Thunderbird inbox full cannot receive email”, then you are landed at the right place. The article here will provide assistance on how to solve the error along with its primary causes. However, read further to explore the solution for addressing the error that occurs when the Thunderbird’s specified size limit exceeds. In case you are searching for perfect solution, consider using MacMister MBOX Converter for Mac & Windows solution that instantly backup Thunderbird mailbox and create space for new emails.

What is Thunderbird Inbox Full Cannot Receive Email Error?

Thunderbird is a free open-source cross-platform emailing program which is introduced by Mozilla foundation. Users with Thunderbird account can easily create, receive, as well as send emails with POP3 and IMAP accounts with many other features. It is equipped with functions including customizable views, fast message search, etc. But with some good options, there are bad ones as well.

At times, Thunderbird prevents users from reading, sending, and receiving regular emails due to the limited storage space. In such a case, an alert message will appear on the screen.

Why Thunderbird Inbox Size Limit Increases Error Occur?

Here, we have highlighted some points highlighting reasons behind why Thunderbird inbox size limit increases –

• The applicant include large amount of email messages and the server is no longer accepting them anymore.
• Using multiple Thunderbird email accounts that have not been cleansed from a very long time.
• The size limit of Thunderbird mailbox folders cannot be extended beyond 4 GB.
• When there is a technical issue with Win OS and Thunderbird v3.1
• Anti-virus or Firewall has either removed or isolated the storage files of Thunderbird.

Solutions to Fix – Thunderbird Inbox Full Cannot Receive Email!

There are two different ways which can be used in troubleshooting the error – Compacting and Deleting. Let’s just understand them one by one –

Compacting

If a single email message is removed from Mozilla Thunderbird, then it will get erased automatically or removed from the email file. However, to delete the files permanently from Mozilla Thunderbird, users need to compact the folders.

Compacting folders is an important task to perform. In case if a user does not perform the same process, then it will keep on increasing and even create different types of problems. The users should compact folders regularly of all mailing programs. And for ease, it can be performed on a weekly basis as well. For a quick process, applicants should make it a habit. Because, if it is not addressed properly, then Thunderbird mailbox full cannot receive email error will surely occur.

Erasing

Installing or configuring Thunderbird app again will not resolve the issue. The issue is with the email files that are not reachable via this approach. Another way is erasing the unwanted and incorrect files could be the option.

Note. Mozilla Thunderbird won’t open the files of new emails. As a result, one may migrate email to another folder available in a local hierarchy.

Users can transfer all the necessary emails simultaneously at the same time. Implement the process by choosing the emails with the help of Shift key and then dragging the same into new folder. Under such situations, the probabilities of resolving the issue completely are minimal. The folders possess small count of deleted emails frequently. As the folder needs some time to copy, the process will eventually be successful after completion.

As a user, it is necessary to understand that in Windows OS whenever a user erases an email from Thunderbird email client, the recycle bin won’t be utilized. The reason for this is the large size files which recycle bin find hard to accommodate. Therefore, in Explorer, you will have an option to rename a file rather deleting it. The approach will carry out smoother operation within Thunderbird app. However, if the problem with large size files remains unresolved and the error highlighting Thunderbird mailbox full cannot receive emails error will persists.

Note. The user will encounter and can observe that every file is linked to the file of the same name with extension MSF. Therefore, while renaming or deleting a file, it is crucial to remove corresponding MSF file. If the process of Thunderbird generating new index fails, then it will lead to indexing problems.

Methods to Follow

Follow the below techniques to fix Thunderbird Inbox full cannot receive email error –

Method 1. Set Settings for Deleted Items

1. Install & run Thunderbird app.
2. Navigate to Tools, select Account Settings and pick Server Settings option.
3. Select Leave Messages on the server.
4. Now, as per the suitable way, choose number of days to manage Thunderbird mailbox limit.
5. Select the option Until I delete them to save the message.
6. Lastly, hit OK button to save the changes.

Method 2. Get in touch with the Email Service Operator

1. By contacting to email service providers, you will be able to increase size of Thunderbird mailbox.
2. Contact the email service operator to delete unnecessary emails stored in the server.

Automated Approach to Fix Thunderbird Inbox Full cannot Receive Email

If the Thunderbird is displaying Inbox full message, then it is probably when the Thunderbird storage is nearly full. So, in order to alleviate the issue, it is important to backup mailbox data and free up the space within mailbox by deleting unnecessary email files.

Alternatively, there is MacMister Thunderbird Converter for Mac & Windows Tool that will help in backing up all the necessary Thunderbird mailboxes into 15+ saving types such as PDF, EML, DOC, TXT, HTML, IMAP, Gmail, Office 365, and more. Its interface is comprehensive and easy to manage. Both professional and novice users will be able to operate the software effortlessly. Additionally, the powerful features of the app will help users saving Thunderbird mailboxes into required saving type according to the requirements. It is available in a free demo as well that allow users to backup 25 Thunderbird mailboxes for free.

Epilogue

In the write-up, we have highlighted different methods to resolve Thunderbird mailbox full cannot receive email error.  Even, if you belong from a non-technical background, you will still encounter a solution which will ease your worries. However, follow the above mentioned methods properly and manage the storage size of Thunderbird email client. For any queries, contact MacMister Support.