The New Thunderbird Email Client
Taking control of your email with Thunderbird: local archiving, file attachments, and storage explained
Thunderbird is a free, open-source email client that puts your data back where it belongs — on your own computer. For small businesses that rely on email for file sharing and record-keeping, it offers a level of control that cloud-only mail clients simply can’t match.
Why local email storage matters for your business
When your email client stores everything in the cloud, your access depends entirely on your subscription remaining active and the provider’s servers being available. If you lose access to your account — through a billing issue, a forgotten password, or a provider policy change — you could lose access to years of business correspondence overnight.
Thunderbird takes a different approach. Your emails are downloaded and stored as files on your local hard drive. You retain a complete, searchable copy of your mailbox that exists independently of any subscription or internet connection.
Attaching and linking files from your computer
One of Thunderbird’s most practical features for small businesses is how it handles file attachments. Unlike web-based email clients that may prompt you to upload files to a cloud service, Thunderbird lets you attach files directly from any location on your computer — including network drives and external storage.
This means you can attach a spreadsheet directly from your local Documents folder, a quote template from a shared network drive, or a scanned invoice from your desktop — all without uploading anything to a third-party service first.
Good to know: Thunderbird also supports Filelink — a feature that lets large attachments be stored on a service like your own server or a cloud provider, with a download link sent in the email instead. This keeps large files out of inboxes while still giving recipients easy access.
Archiving email to a local drive
Thunderbird has a built-in archiving feature that moves older emails out of your inbox and into a structured local archive, organised by year and month. This keeps your inbox manageable while ensuring nothing is deleted.
To set up local archiving:
In Thunderbird, go to Tools > Account Settings and select Copies & Folders for your email account.
Under the Archives section, choose Keep message archives in and select Local Folders from the dropdown. This stores archived mail on your computer rather than on the mail server.
To archive an email or a batch of emails, select them and press the A key, or right-click and choose Archive. Thunderbird will sort them into folders by year automatically.
Your archived mail is stored in Thunderbird’s local profile folder on your hard drive. You can locate this via Help > Troubleshooting Information > Open Profile Folder.
Back up your profile folder: Because your archived email lives in Thunderbird’s profile folder, it’s important to include this location in your regular backup routine. Losing this folder means losing your archive. A simple copy to an external drive on a weekly schedule is sufficient for most small businesses.
Storing your Thunderbird profile on a specific local drive
By default, Thunderbird stores its profile (which includes all your mail, settings, and archive) in a system folder on your C: drive. If you’d prefer to store your email data on a separate drive — such as a dedicated data drive or a large external drive — this can be configured when setting up Thunderbird, or by moving the profile folder and pointing Thunderbird to the new location via the Profile Manager.
This is particularly useful if your C: drive is an SSD with limited capacity and you want to keep mail archives on a larger secondary drive without involving any cloud service.
What Thunderbird doesn’t do
Thunderbird is a capable email client, but it’s worth being clear about its limitations. It doesn’t have a built-in calendar that syncs to your phone out of the box (though the Lightning add-on extends this), and its interface is more functional than polished. For businesses already deep in the Microsoft 365 ecosystem, switching requires some setup time and a willingness to manage your own backups.
That said, for businesses that value data ownership, want to reduce subscription dependency, and need reliable local archiving, Thunderbird is a well-proven solution that has been in continuous development for over twenty years.
Need help getting set up?
If you’d like help configuring Thunderbird for your business email account — including setting up IMAP, configuring local archiving, or migrating from another email client — your own IT support team is a great first point of contact. If you don’t have in-house IT support, feel free to get in touch with us and we can walk you through the process or handle the setup on your behalf.
NZ Servers provides web hosting and email services to businesses across New Zealand, Australia, and the Pacific. nzservers.com