Guide prepared 9 September 2026 · Examples use fictional emails
Export your mail from Google.
Use Google Takeout to export the Mail data you need. Google controls export availability and delivery. Follow Google’s official export instructions for your account.
Extract the downloaded archive.
If Google supplies a ZIP, extract it using your computer’s archive utility. Locate the mail folder and the file ending in
.mbox. Folder names can vary. This viewer opens that MBOX file; it does not open the surrounding ZIP or compressed archive.Open the MBOX file in the viewer.
Choose Open MBOX file and select your extracted file. There is no fixed limit on the archive’s file size. The viewer supports up to 100,000 messages and 64 MiB per message; large archives take longer to open and other processing limits apply. Changing Takeout’s download archive size does not guarantee a smaller MBOX. Gmail exports by timeframe are not supported in Takeout; see Google’s export help. Renaming a ZIP or PST does not convert it to MBOX.
Find a conversation or attachment.
Search by sender, subject or attachment filename. Filters can narrow the sender, UTC dates and file extension. Messages without a readable date are excluded when a date filter is active. Gmail labels and Gmail search operators are not supported.
Review and download your files.
Select attachments and choose Review export. The ZIP contains the files and a source-message index. Extract the ZIP before opening its index. Source emails are optional and contain the whole selected messages, not only the separately selected attachments.
If a file will not open
Check that it is the extracted MBOX, within the displayed size limits. Incomplete messages, unsupported container variants and excessively large individual messages cause the import to stop with an explanation. Keep the original export. This viewer cannot repair a damaged archive or recover access to an email account.
Compatibility is exercised on synthetic MIME and conventional MBOX fixtures. This guide does not claim that every current Takeout variant has been tested. Google Takeout and Gmail are Google products; MBOX Studio is independent.