MailFundusEmpty mailbox. Keep everything. Find it instantly.
MailFundus Archive backs up your mailboxes byte for byte into an archive on your Mac and verifies every single message. Only then does it tell you what can go from Mail. The archive is less than half the size of Mail, and every search takes milliseconds, even inside attachments.
Free to download, up to 500 messages free · full version US$24.99 once, no subscription (price varies by country) · for businesses MailFundus Pro: US$129 a year or US$12.99 a month, free for 14 days · macOS 15 or later · no account, no cloud · everything stays on your Mac
Mailboxes
Years
Delete from Mail…
A real archive: 76,104 messages, twenty years of mail.
Every figure on this page comes from one real archive on a MacBook Pro with an M1 Max. No lab values, no extrapolation.
Back up first, verify second, clean up last.
The order is the product. MailFundus Archive does not touch Mail until every message is provably in the archive.
Keep everything
Every message is stored, read back, and compared byte for byte with the original. Attachments, headers, formatting: nothing is lost, nothing is converted.
Find it instantly
Full-text search across all messages and attachments, in milliseconds. By sender, subject, body, attachment name, and for PDF attachments by what is inside them. Even across twenty years of mail.
Empty mailbox
What is backed up and verified, MailFundus Archive moves to Mail's Trash, and only that. You empty the Trash yourself, with the verification list in front of you. Two separate steps, two deliberate decisions.
Twenty years of mail. One search field. No waiting.
Search covers subject, sender, recipients, body, and attachment names. For PDF attachments it covers their contents as well. The invoice that only ever existed as an attachment turns up by its invoice number.
- Milliseconds, not minutes. "contract cancellation": 770 results in 14 ms. "invoice": 9,701 results in 27 ms. Measured with 76,104 messages. With filters it stays under 60 ms.
- Hits inside attachments. If the term is in a PDF, the results list says so. You open attachments with Quick Look, just like in the Finder, no detour.
- The filters you actually need. Mailbox, year, "with attachment only". And "Zürich" also finds "Zurich".
19.3 GB of Mail becomes 8.6 GB of archive. Without a single byte missing.
Byte-exact and still less than half the size. That is not a contradiction. It is four things Mail never does.
Every message only once
The same email in "Inbox", "Archive", and "Project"? Mail stores it three times, MailFundus Archive once, and remembers all three locations. In the example: 9,895 copies saved.
Every attachment only once
The proposal that went back and forth five times sits in the archive once. 3,779 attachments used more than once saved 2.48 GB.
No Base64 overhead
Mail keeps attachments as text, a third larger than the file itself. MailFundus Archive stores them in binary form and rebuilds the text byte for byte when you restore. In the example: 3.69 GB.
Text compressed, attachments left alone
Message text shrinks sevenfold, from 5.13 GB to 711 MB. PDFs and photos are usually compressed already and only get a little smaller. So a mailbox full of photos ends up about half the size, and a text mailbox becomes tiny.
One path, five stations. The app leads the way.
“Back Up to Archive…” is the one button you need. Everything else runs on its own and stops wherever a decision is yours to make.
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Select
Which mailboxes go into the archive? Count and size are shown next to each one. Set an age limit if you like: older than a number of days, weeks, months, or years, everything before a date, or simply everything. What is recent stays in Mail.
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Back up and verify
Archive, compare byte for byte, restore a sample. Mail stays untouched. You can stop a run safely at any time. What has been read is sealed, and the next run picks up where it left off.
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Delete from Mail
The safety line sits above everything: "12,408 messages archived and verified byte for byte. Safe to delete from Mail now." You see the list of verified mailboxes and confirm. Only then does MailFundus Archive move those messages to Mail's Trash, through Mail's own scripting interface, each one verified against the archive once more right before. Messages whose attachments Mail never downloaded stay put on purpose. If you would rather delete in Mail yourself, choose “Delete in Mail Yourself…”. The app shows what is safe to delete and checks afterwards with “Deleted in Mail, Check Now”.
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Trash
You empty the Trash yourself, in Mail: Mailbox → Erase Deleted Items. Only then does disk space become free. Afterwards click “Trash Emptied, Update Now”: MailFundus Archive asks Mail what is really gone and records it in the archive. The app never deletes anything permanently.
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Done, and find it again
Three answers: what was backed up, what is out of Mail, and where you find it now. Search, read, open attachments with Quick Look, just like in the Finder. “Restore to Mail…” writes a message out as .mbox or .eml, and you import that file into Mail. And “Show in Mail” jumps to the original mailbox.
What MailFundus Archive does not do, and why.
An archive is only as good as the trust you place in it. So here is what others put in the fine print.
- It never deletes anything unverified. No run reaches Mail until every message has been read back and compared. If a check fails, nothing happens in Mail. Messages move only after you confirm, and only to Mail's Trash. You empty that yourself.
- It converts nothing. No PDFs, no database interpretation. The archive holds each message exactly as Mail stored it, byte for byte.
- It asks before it reads. Mail's storage is protected by macOS. You grant access to the Mail folder once in the Open dialog, and that is all the app needs. It only reads there. And the first time you reach the step “Delete from Mail”, macOS asks you whether MailFundus Archive may control Mail.
- It tells no one anything. No account, no sign-in, no statistics, no server of ours for your data. The app loads the manual from our website. It also asks the App Store, through Apple's purchase interface (StoreKit), for prices and for your purchases. Apple handles that connection. We receive no purchase or payment data and no data about you. Only with MailFundus Pro, and only if you want, the app also reads IMAP accounts you add yourself: read-only, directly between your Mac and your mail server, with the password kept in the keychain.
- It does not lock you in. The archive is a file on your disk. Any message can be written out as .eml or .mbox at any time, even without MailFundus Archive.
- It is on the Mac App Store. Reviewed by Apple, updates arrive automatically. The download is free. You buy the full version and MailFundus Pro in the app through Apple, and there is no sign-in with us.
Keeping records is not optional. It is required.
Business email is business correspondence. In Germany, Section 257 of the Commercial Code, HGB, and Section 147 of the Fiscal Code, AO, require you to keep the proposals, invoices, and contracts you send or receive by email. Most other countries have similar rules for tax and company records. Deleting in Mail is only fine once an archive exists that is complete and stays complete.
That is exactly the point where most mailboxes either grow without end or quietly develop gaps. MailFundus Archive solves both in one pass: first everything is provably in the archive, then Mail gets light.
| What, in Germany | How long |
|---|---|
| Business correspondence: proposals, orders, letters | 6 years |
| Accounting records: invoices, credit notes, bank statements | 8 years |
| Annual accounts, balance sheets, inventories | 10 years |
The period starts at the end of the calendar year in which the email was written or received. The eight-year period for accounting records applies since 2025.
What MailFundus Archive contributes
The German bookkeeping rules, the GoBD, ask four things of an archive. This is how MailFundus Archive answers:
- Complete for the selected mailboxes. The counts in Mail and in the archive have to match before anything is deleted.
- Unchanged. Every message carries a checksum. Deviations are detected at every verification and named in the verification log.
- Available. Full-text search across years in milliseconds, export as .eml or .mbox, for the auditor too.
- Traceable. A log for every run: what was backed up, what was verified, what was deleted, and when.
Not legal advice. MailFundus Archive is an archiving tool, not a certified compliance system. Process documentation and the question of which emails you are required to keep remain the responsibility of the business. When in doubt, ask your tax advisor.
For businesses: MailFundus Pro
MailFundus Pro is an in-app subscription. It includes the full version plus everything a small business needs to keep its email in a traceable way: scheduled backups, a seal chain against unnoticed changes, retention periods, access for the auditor, and procedural documentation.
- Automation. MailFundus backs up on a schedule, hourly, daily or on weekdays, from Mail's folder and optionally directly from the mail server (IMAP). Every run is verified byte for byte; anything missing appears in the gap report. Nothing is deleted.
- Seal chain and write protection. Every run is sealed, and sealed files are set read-only. Any later change to messages, files or logs is detected by the check. A second copy of the seals is kept in another location.
- Retention with a deletion lock. Retention periods per account or mailbox. Nothing can be removed before the period ends; after that, a deletion run cleans up and keeps a log. Mailboxes can be marked as private.
- For auditors. Read-only auditor access, limited to a period and without private messages, plus an auditor export with a checksum for every file.
- Procedural documentation. The app generates it from its settings, you add the company's details, and you get a PDF.
Several Macs
Exactly one Mac writes to the archive: the archive Mac, ideally one that stays on, such as a Mac mini. A write lock makes sure no second Mac writes to it. Other Macs open the archive read-only through a read copy, for example from a NAS, and need no subscription for that. One subscription covers every Mac signed in with the same Apple Account.
Resellers and IT providers who look after customer Macs can reach us at info@coolblack.gmbh.
MailFundus Pro
US$129 a year or US$12.99 a month
- Prices vary by country; in Germany €149 a year or €14.99 a month. The App Store shows the exact amount.
- If you subscribe to Pro for the first time, you try it free for 14 days. Cancel before then and you pay nothing.
- One subscription covers every Mac with the same Apple Account.
- Purchase and billing through Apple. Cancel any time in your Apple Account settings.
Your purchase stays yours: if you bought the full version, you keep it with everything it does. The free version and the full version stay as they are. If Pro ends, the archive, seals and logs stay readable, searchable and exportable.
MailFundus Pro on the Mac App StoreSubscribe in the app: MailFundus Archive → MailFundus Pro… · Pro in the manual
Not legal or tax advice. MailFundus Pro supports GoBD-compliant archiving (German record-keeping rules) when set up and used properly. There is no official certification for this. Organizational measures and the question of which emails you are required to keep remain the responsibility of the business. When in doubt, ask your tax advisor.
An empty mailbox, and every message kept.
MailFundus Archive is free to download from the Mac App Store. The free version backs up your first 500 messages with every feature, and the full version removes the limit: US$24.99 once, no subscription. For businesses there is MailFundus Pro, a subscription that is free for the first 14 days. The manual shows you what the guided path looks like.
Download free on the Mac App Store Read the manual