Storing business email: retention obligations and archiving

How long do you need to keep business email, and are you allowed to keep everything? In this article you'll read what the retention obligation and the privacy rules say, using the Netherlands as an example, and how to archive your mail in practice. This is a general explanation, not legal or tax advice. Retention periods differ per country, so check with your tax authority, your bookkeeper or your accountant.

1. Which mail falls under the retention obligation?

In many countries a business has to keep its records for a number of years. Mail is part of those records if it contains agreements or data relevant to your bookkeeping or taxes. For example:

• quotes, order confirmations and agreements about prices;
• invoices you send or receive by mail, including the attachments;
• contracts and any changes to them.

Newsletters, advertising and ordinary messages without financial consequences usually don't need to be kept.

2. How long? The example of the Netherlands

• The period only starts once a document is no longer current. A contract that runs for four years is kept for those four years, and then for another 7 years.
• If your business closes, the retention obligation still applies.
• Keeping records digitally is allowed, as long as you can show the documents within a reasonable time and they can't be changed unnoticed.

The rules can be found on the website of the Belastingdienst (the Dutch Tax and Customs Administration). Other countries have different periods.

3. The privacy side: no longer than necessary

Mail often contains personal data. Under the GDPR (AVG in Dutch), you don't keep personal data longer than necessary for its purpose. That doesn't conflict with the retention obligation: what you're legally required to keep, you may keep. But keeping everything forever just because you can is not the idea.

• Decide for each type of mail how long you need it, and write that down.
• Clean up mail with no business value, such as old job applications or contact form messages.
• Keep the archive as secure as your mailbox: with a strong password and a backup.

Read more about the GDPR and your website in GDPR for your website: cookies, external content, forms and privacy statement.

4. How to archive mail

There are a few ways. You can also combine them.

1. An archive folder on the server. Move old mail to a folder such as Archive or Archive 2025. The mail stays available in webmail, on your phone and in our nightly backup, but it counts towards your mailbox storage. See Folders in your mailbox: Inbox, Sent, Drafts, Trash, Junk and Archive.
2. Save locally. Move mail to a local folder in your mail program, such as a .pst file in Outlook or Local Folders in Thunderbird. This saves space on the server, but the mail is then only on that computer. See Saving mail locally to free up space on the mail server.
3. Export individual messages. Save an important message as an .eml file, with the attachments included. See Exporting a message as .eml and importing it again. Put such files in a fixed folder in your Nextcloud, for example, alongside your other records.

5. Cancelling a mailbox or a package?

Then export the mail you need to keep before the end date. After the end date the package stops immediately. Read how to take everything with you in Leaving WebOké: how to take your data with you.

Detailed explanation with screenshots: Archiving: an archive folder on the server or a pst file in the Outlook manual and Archiving messages in the webmail manual.

Want to learn more? Take the free course Email in order, lesson 3.2 Storage, quotas and a full mailbox.