MBOX to PST

Convert one or more MBOX mailbox files into a single Unicode Outlook PST. The conversion preserves every message’s full headers, HTML or plain-text body, and all attachments, and the resulting PST can exceed the old 2 GB size limit. The output PST contains one "Inbox" folder where all messages are merged; separate MBOX files are not retained as distinct folders.

All messages merged into a single Inbox folder

The converter creates one folder named "Inbox" at the root of the resulting PST file. Every email extracted from each uploaded MBOX archive is placed into this folder, so the output contains a single, flat list of messages instead of a hierarchy that mirrors the source files.

File names of the source MBOX archives are not turned into sub‑folders. When several archives are submitted together, their messages are appended sequentially in the order the files were uploaded, preserving the original chronological order inside each archive and producing a continuous Inbox view.

Unicode PST output that exceeds legacy 2 GB limit

The generated PST uses the Unicode format introduced with Outlook 2003 SP3, which removes the 2 GB size ceiling of the older ANSI PST. This allows the output file to grow well beyond two gigabytes, making the converter suitable for large mail archives that would otherwise exceed legacy limits.

Conversion is performed on a server‑side temporary file rather than in memory, so the only practical limitation is the upload‑size cap associated with the user’s account tier. As a result, even very large source archives can be processed without exhausting RAM, provided they fit within the allowed upload quota.

Complete header transfer, including Bcc

All standard envelope headers—From, To, Cc, Subject, and the original Date—are mapped directly onto Outlook’s native fields so that each message retains its metadata exactly as it appeared in the source MBOX. This ensures that sorting, searching, and threading in Outlook behave identically to the original client.

The converter also preserves Bcc recipients when they are present in the original message. Unlike many conversion pipelines that strip Bcc information, this tool retains those hidden addresses inside the PST item, allowing a faithful reconstruction of the message as it was originally sent.

HTML and plain‑text bodies retained as‑is

When a message contains both an HTML part and a plain‑text alternative, the converter stores both parts inside the Outlook item. Outlook then decides which representation to display based on the user’s preferences, so the recipient sees either the richly formatted version or the simple text version exactly as intended.

The HTML body is transferred without re‑encoding or alteration, preserving paragraphs, lists, tables, bold, italic, and inline styles. Likewise, the plain‑text alternative is kept unchanged. This one‑to‑one transfer guarantees that the visual appearance and formatting seen in the original client are reproduced faithfully in Outlook.

Attachments and inline images preserved

All binary attachments—including PDFs, ZIP archives, DOCX files, images, and any other file types attached to the original email—are transferred to the PST as native Outlook attachments. They appear in the message exactly as they would if the email had been received directly in Outlook, with no loss of data.

Inline images referenced with cid: identifiers survive as multipart attachments and are rendered inline by Outlook using the same CID lookup mechanism. External image URLs (http/https) remain in the HTML body as links; Outlook fetches them at view time according to its own external‑content policies, ensuring the message’s visual content is preserved.

Limits and scope

Download link lifespan

The generated .pst file can be downloaded for 24 hours after conversion finishes.