Emails contain quotes, orders, invoices, and agreements. Many of these documents are subject to statutory retention obligations, regardless of whether they exist on paper or electronically. In Austria, for example, books, receipts, and business letters must generally be kept for seven years under the Unternehmensgesetzbuch (Austrian Commercial Code) and the Bundesabgabenordnung (Austrian Federal Fiscal Code); in Germany, retention periods of up to ten years apply, depending on the type of document.
The mailbox itself is unsuitable as storage for this: messages are deleted or moved, mailboxes hit size limits, and after an employee leaves, the mailbox is often no longer accessible.
How does email archiving work?
An archiving system automatically captures incoming and outgoing emails, often as early as when they pass through the mail server via so-called journaling, that is, before they can be deleted in the mailbox. The messages, including attachments, are stored in a tamper-protected manner, for example with checksums or on immutable storage areas.
Full-text search enables authorized persons to find messages by sender, time period, or content. Retention policies define how long messages are kept and when they are deleted. Access to the archive is logged.
Typical examples
- During a tax audit, invoices and correspondence from past years are required.
- In a legal dispute, it must be proven when a quote was sent and with what content.
- After an employee leaves, business correspondence remains findable for the successor.
What companies should keep in mind
- Clarify which emails are subject to retention obligations and which periods apply, and coordinate this with your tax advisor.
- Take the GDPR into account: archived data must also be deleted after the retention periods expire, and access must be restricted to authorized persons.
- Clearly regulate private use of the business email address, because archiving private messages is sensitive under data protection law.
- For cloud mailboxes such as Exchange Online, check whether the built-in retention features meet the requirements or whether a separate archive makes sense.
How it differs
A backup serves to restore systems and data after an outage, and older backup versions are overwritten after a defined time. An archive retains individual messages long-term, unchanged, and findable. The two complement each other but do not replace each other.
This entry is a general overview and does not replace legal advice.
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