Securely Back Up, Archive & Migrate Emails

Emails often serve not just as a communication channel but also as a valuable archive of critical information—ranging from conversations and contact details to links, serial numbers, and file attachments. Whether you have a carefully organised folder structure or a single ever-expanding inbox, safeguarding these messages is vital. Below, you’ll learn how to create reliable backups, archive emails independently of any specific mail application, and migrate data to a new mail client or provider.

Why You Need a Backup

Relying solely on your email provider’s server or your mail programme’s storage can be risky. Servers can fail, accounts can become inaccessible, and local email databases can get corrupted. Creating your own backup ensures you maintain control over your data and can recover important messages if something goes wrong.

Export Options in Mail Clients

Most desktop mail applications include some method to export folder contents. The exact process and file formats depend on the client:

• Microsoft Outlook usually exports to PST files. These can contain entire folder structures, emails, contacts, and calendar entries.
• Mozilla Thunderbird can export using add-ons like ImportExport Tools NG to produce EML, MBOX, or even PDF archives. Its built-in feature can package messages, settings, and address books into a ZIP, though large files (over 2 GB) may cause problems. Thunderbird also stores emails internally as MBOX files, one per folder, which you can copy directly from the profile folder.
• Apple Mail can export in formats including EML or PDF, depending on the version.
• Other Clients often default to EML or MBOX. Both are plain-text formats suitable for long-term archiving and cross-client migration.

Tip: If you want a format readable without any mail client, PDF is a universal choice. However, most programmes do not offer PDF as a standard export. You may need an add-on or a virtual PDF printer to convert your emails into PDF documents.

Key Email Archive and Export Formats

• PST: Proprietary to Microsoft Outlook. It can contain emails, folders, contacts, and calendars. Great for transferring data between Outlook installations but less compatible with other clients.
• OST: Used by Outlook as a local cache for IMAP and Exchange. Not portable and unsuitable for backups or transfers.
• MBOX: A plain-text file that can store multiple emails in sequence, often used by Thunderbird and many other clients.
• EML: Another plain-text format, typically containing one message per file. Widely supported by a range of mail programmes.
• MSG: Outlook’s format for individual messages, stored in a partially binary form.

If your new mail programme struggles with the format your old application creates, consider a dedicated conversion tool, such as MailStore Home, which can read from PST or MSG and export to more universal formats like EML or MBOX.

Creating Independent Archives

To ensure your archived messages are accessible even if a particular email programme becomes obsolete, keep them in common formats like EML or MBOX. This approach allows you to open or re-import the messages in other mail clients later. If you choose PDF for maximum independence, remember that it’s not as straightforward to re-import PDF documents into a mail programme or extract attachments afterward.

Migrating to Another Mail Client

If your email accounts use IMAP or Exchange, migration is usually simple:

1. Install and open your new mail client.
2. Add your account credentials.
3. Let the new client synchronise everything from the server.

IMAP and Exchange store emails (and, in the case of Exchange, calendar events and contacts) on the provider’s server. Your new mail client simply downloads or syncs a copy.

POP3, however, typically moves messages from the server to your computer. If you’ve been downloading and removing emails from the server, you’ll need to export them from your old client (for example, as PST or MBOX) and then import them into the new one.

Switching Email Providers

When changing providers and wanting to keep all your messages:

1. Add the New Account: Most mail clients allow multiple accounts. Sign in to your new provider alongside your old one.
2. Copy Folders: Create any custom folders on the new account and drag your messages from the old account’s folders to the new ones.
3. Synchronise: Wait for the client to upload these messages to the new server.

If that’s not possible, export your messages from the old account (PST, MBOX, or EML) and import them into the new one.

Some providers offer an automatic migration service that copies your data if you supply the login credentials for your old mailbox. If you choose this option, it’s wise to change the old account’s password after the migration finishes.

Backing Up and Converting with MailStore Home

MailStore Home (for Windows) is free for personal use. It can:

• Archive messages directly from your email client or mail provider’s server.
• Store them in a dedicated, searchable database.
• Export them in multiple formats for backup or migration.

This tool also features a powerful search function, often more efficient than that of many email programmes. You can search by sender, recipient, date ranges, attachment size, and more. Attachments are archived too, and their contents can be indexed if they are supported file types (e.g., PDF, Office documents).

Tip: MailStore Home does not decrypt end-to-end-encrypted emails. If you rely on encryption, you’ll need to ensure messages are decrypted in your mail programme before archiving.

Once you’ve created an archive, you can:

• Automatically update it by running MailStore Home on a schedule.
• Export messages or whole folders to a new mail provider, a different mail client, or standard file formats (MBOX, EML, PST).

For businesses requiring more advanced compliance features, there is a separate paid edition, MailStore Server, which adds journaling, automation via command-line tools, and other enterprise-grade capabilities. However, private users typically find MailStore Home sufficient for personal archiving and migration.

Conclusion

Email backups and archives are essential for preserving important messages and attachments, safeguarding against technical failures, and facilitating easy moves between mail clients or providers. Whether you use built-in export tools in Outlook, Thunderbird, or another programme—or rely on a dedicated solution like MailStore Home—you can keep your email data safe and accessible for years to come.