The most effective MBOX file splitter software allows you to split a large MBOX file based on size, date, date range, sender or subject without any loss of emails, attachments or metadata. A few paid software tools come with the provision of downloading the application software for free in Windows and Mac versions with a free trial.
What Are The Reasons For MBOX Files Becoming Unnecessarily Big?
The reason behind the big sizes of MBOX files is that these files consist of all emails in the mailbox in one text file. Although there isn't any limit to file size in this format, the collection of many emails over the years along with large files and full mailbox export (especially Google Takeout export of the whole Gmail account to a single MBOX file) often exceed 4GB, 10GB, and sometimes even bigger sizes.
The main problem is experienced by Thunderbird, the most popular client using MBOX format.
Indications That Your MBOX File Needs to Be Split Up
Mozilla Thunderbird generates an "exceeded maximum request size" or some other kind of a large mailbox error.
Mail application hangs/freezes when you attempt to open a certain folder.
You receive an error saying that there are no valid MBOX files in the directory even though the file is there.
Email backups/exports/transfers take too long or fail due to the file size.
You need to archive a large mailbox by years or per sender.
What Splitting of an MBOX File Actually Means?
An appropriate MBOX splitter analyzes the message boundaries within the file (unlike a file splitter which splits by byte position) and creates several valid MBOX files that can be opened separately without any further rejoining. It is this feature that makes an MBOX splitter different from the generic large file splitting on a byte level would damage an MBOX file and cut messages in half.
Offline MBOX Splitters:
Keep all your email data locally.
Usually faster when splitting very large files.
Download/installation of software required.
Online MBOX Splitters:
No installation required use from within the web browser.
Ideal solution for a once-in-a-while quick splitting job.
Involves uploading your email data to a third-party server, which is definitely a privacy issue for business, legal or personal communication.
Offline application is the better choice in case of sensitive or large mailboxes.
Method 1: Split MBOX File Using Professional Software for Best Large File Splitter Free To Download.
SysTools MBOX Splitter is a desktop utility available for Windows/Mac to split MBOX files by size, date, date range, sender or subject with all attachments, folders structure and metadata (To, From, Subject, Date).
Procedure:
Install that splitter on Windows/Mac.
Click Add File/Add Folder to add your MBOX file/folder.
Review the loaded emails and attachments to ensure the correct data imported.
Select the splitting option:
Split by size: Choose any size from 1 MB to 20 GB per output file.
Split by date: Split the email messages before/after the selected date.
Split by date range: Split email messages between the specified two dates.
Split by year: Split into one file per year.
Split by sender or subject.
Select the destination folder for output files.
Split and verify the opening of sample
Method 2: MBOX Splitting Method Which The Best Large File Splitter Free To Download
It allow you to upload an MBOX file via dragging and dropping and then split it based on file size, year, or sender.
Pros: simple procedure, no software installation.
Cons: suitable only for casual splitting of emails due to uploading email content to a remote server.
Method 3: Manual Editing for Best Large File Splitter Free To Download
Strictly speaking, you could open a small MBOX file in a text editor and manually transfer segments of it to separate files, making a cut every time you see "From " which denotes the beginning of a new message. However, it would be reasonable only for very small files containing only several emails in any case where it is really necessary to split an MBOX file, this method is simply not feasible and highly prone to errors.
What are the Typical Issues and Solutions for Best Large File Splitter Free To Download?
Thunderbird fails to open the file even after splitting.
Import the split files one by one instead of trying to open them all at once as one combined MBOX file all the split files are individual MBOX files.
Attachments are not there after splitting.
Make sure you have used MBOX file splitter and not a general purpose file splitter. Using a byte level file splitter will destroy the attachments.
Slow Splitting of the file due to very large file size.
Normal for files in tens of gigabytes. Make sure you have ample amount of disk space (equal to the size of the source file) available for output.
Some emails look missing after splitting by date.
Verify date range and timezone settings those emails which are slightly beyond your selected date range would not come under this particular split file.
What are The Best Practices for Best Large File Splitter Free To Download?
Always make a copy of the MBOX file prior to splitting.
Try the free demo first on a smaller dataset before purchasing the software license.
Pick a split strategy that meets your real requirements whether by size for storage/performance reasons, by date/year for organization purposes, or by sender or subject for filtering of specific correspondence.
If the content of the mail is business-sensitive, legal, or just plain sensitive, use an offline desktop tool to split it, not an online one.
Check a few output files after splitting in your mail client to verify the message counts and attached files.
Frequently Asked Questions
Q1. Are these the best large file splitter free to download?
Answer. Yes, Most dedicated MBOX splitters provide a free demo version that splits a certain amount of messages in order to let you try out the software.
Q2. Is it possible to lose data while splitting an MBOX file?
Answer. No, Splitting using a dedicated MBOX splitter will not result in losing anything. The generic file splitter on byte level, however, can damage your MBOX file.
Q3. Is it possible to split an MBOX file online?
Answer. Yes, but at your own risk. There are online services to split MBOX files, which means your email content
Q4. How can I rectify Thunderbird's large mailbox issue?
Answer. Split your large MBOX file into small files by using an MBOX file splitter, and re-import these small files back into Thunderbird.
Q5. How does an MBOX splitter differ from a generic file splitter?
Answer. An MBOX splitter splits the MBOX file by messages, whereas a generic file splitter will split the file in random places and hence corrupt it and is the Best Large File Splitter Free To Download.
Q6. Is there any necessity of joining the split MBOX files again?
Answer. No, Splitting MBOX files results in independent MBOX files that can be used individually.
Conclusion
In case Thunderbird has problems with MBOX files which are too large, or you just wish to make your MBOX archives more manageable, you will need to use a special MBOX splitter, not a simple file splitter. There are reliable free demos of professional software which provide efficient splitting of MBOX archives using criteria like size, date, and sender without changing any data or attachments, which can be used on Windows machines and are best large file splitter free to download. In case the emails contain sensitive data, use only an offline solution.
