MBOX is a stream
Clients like Thunderbird write a single mailbox file. Splitting is the usual first step before another system, a review, or a PST build.
Unix mailbox
MBOXEML
Split MBOX to EML
MBOX concatenates messages in one file. That is efficient to store and painful to open elsewhere. Splitting to EML gives you one RFC 822 file per message, which most tools already understand.
No account on the public uploader. Guest jobs stay within five conversions and 250 MB per day. Business rates start at €0.80/GB for OST → PST.
Talk to the AI — it replies
IACOPO
Describe what you want, then continue to convert.
Validation
We check that the split produced mail, not a truncated copy of the original blob. Empty or unreadable MBOX files are rejected with a diagnostic.
Apple Mail and Thunderbird
Both families emit MBOX-like files. Upload the mailbox file, not a random .emlx bundle, unless that is truly what you have.
Questions
Do I lose read/unread flags?
EML carries the message. Client-specific flags often live outside the MBOX payload and may not transfer.
Can I go straight to Outlook?
Yes — use MBOX to PST when the destination is Outlook rather than loose EML files.
Is the output one EML or a zip?
A mailbox becomes a set of messages, delivered as a zip of EML files.