How to Export or Back Up a Business Mailbox (IMAP Copy, Local Archive)

Your mail host keeps your mailbox online, but a host is not a backup: an accidental delete, a compromised password, a closed account or a company dispute can all remove access to years of correspondence. Backing up a business mailbox is cheap and mostly automatic once set up. Here are three methods, from a one-off export to a nightly sync.

Quick summary

• Add the mailbox to Thunderbird or Outlook over IMAP (mail.oqumail.com, port 993, SSL/TLS). Set the account to download full messages, not headers only; in Thunderbird this is Account Settings, Synchronization and Storage, "Keep messages for this account on this computer".
• Wait for the download to finish. A 3 GB mailbox on a home connection can take a few hours.
• Thunderbird: install ImportExportTools NG, right-click the account, Export all folders as mbox. Outlook: File, Open and Export, Import/Export, Export to a file, Outlook Data File (.pst), select the account, include subfolders.
• Copy the resulting file to your normal business backup location (external drive, cloud storage with versioning).
• Repeat quarterly, or whenever a major project ends.

Method 1: one-off export from a desktop app

1. Add the mailbox to Thunderbird or Outlook over IMAP (mail.oqumail.com, port 993, SSL/TLS). Set the account to download full messages, not headers only; in Thunderbird this is Account Settings, Synchronization and Storage, "Keep messages for this account on this computer".
2. Wait for the download to finish. A 3 GB mailbox on a home connection can take a few hours.
3. Thunderbird: install ImportExportTools NG, right-click the account, Export all folders as mbox. Outlook: File, Open and Export, Import/Export, Export to a file, Outlook Data File (.pst), select the account, include subfolders.
4. Copy the resulting file to your normal business backup location (external drive, cloud storage with versioning).
5. Repeat quarterly, or whenever a major project ends.

Method 2: keep a live IMAP copy in a second mailbox

1. Create a mailbox called archive@ on your domain. On OquMail it is one of the 15 free mailboxes with its own 5 GB.
2. In a desktop app, add both accounts and copy (not move) folders from the working mailbox to archive@ at the end of each month.
3. The archive mailbox is now searchable from webmail on any device and is independent of the working mailbox's password.
4. This protects against deletion and account compromise but not against the host itself disappearing, so pair it with method 1 or 3 once a year.

Method 3: automated sync with a tool

• Command-line tools such as imapsync, OfflineIMAP or mbsync (isync) copy a mailbox to another IMAP server or to local Maildir files and can be scheduled nightly. They need someone comfortable with a terminal.
• Many desktop backup tools (and some NAS devices) include an IMAP mailbox backup module that runs on a schedule with a simple form: server, port 993, username, password.
• Whichever tool you choose, use a dedicated app password or a mailbox created for the purpose, and store credentials in the tool's own encrypted store, not in a script.

Test the restore

A backup that has never been opened is a hope, not a backup. Once a year open the mbox in Thunderbird (ImportExportTools NG, Import mbox file) or the .pst in Outlook (File, Open, Open Outlook Data File) and search for a message you know exists. Check an attachment opens. Ten minutes of testing turns a file into something you can rely on.

Pitfalls

• Exporting from a phone app. Phone apps only hold recent mail; always export from a desktop app that has downloaded everything.
• Outlook's "headers only" IMAP mode. The .pst will contain subjects with empty bodies. Set the account to download full items first.
• Storing the only copy on the same laptop. Laptops are lost and stolen; backups belong in a second place.
• Forgetting Sent. Most exports include all folders by default, but check the folder list before you start.
• Personal data. An exported mailbox contains customers' personal information; keep it as protected as the live mailbox.

Common questions

How big will the export be?

Roughly the same as the mailbox size shown in webmail; mbox is slightly larger because attachments are stored base64-encoded. A typical small-business mailbox is 1 to 3 GB after a few years.

Can I back up a shared mailbox the same way?

Yes. Add it as another IMAP account in the desktop app using its own username and password and export it like any other. Shared support@ mailboxes are often more valuable than personal ones, so include them.

Does the host keep its own backups?

Reputable hosts back up their infrastructure for their own disaster recovery, but that is not the same as restoring a single message you deleted last month. Treat any host's backups as their safety net, and keep your own copy as yours.