Backup and moving

Last updated October 2026

Your emails live on the mail server and are safe there. Everything else (notes, rules, contacts, follow-ups) exists only on your device. Without a backup, a defect means it is gone.

Full backup

The easiest path is the built-in backup. It contains the entire database with emails, contacts, tags, notes, rules, smart folders, signatures, templates and keys, plus the settings, the credentials and the emails in Local Folders. Not included are mails currently waiting in the outbox to be sent.

1. Open Settings → Import / Export.
2. In the Full backup section, click Export full backup.
3. Choose where to save.

The file is named youniqmail-full-backup-<timestamp>.json and is roughly as large as your database and your Local Folders combined. With a lot of mail, that is easily several gigabytes. Despite the .json extension, it cannot be read in a text editor; it is meant for YouniqMail.

The backup file is confidential

It contains your complete mail database, all settings, your license data and your credentials. The credentials are bound to the original device, while the database and the Local Folders are encrypted the same way as on your device. If storage encryption is off, your mail sits in it readable. There is no separate password for the file. Treat it like a password document, and do not put it unprotected into a cloud.

Restoring a backup

1. Close all other YouniqMail windows and open Settings → Import / Export.
2. In the Full backup section, click Import full backup.
3. Select the backup file.

Once everything is restored, YouniqMail restarts on its own. Before that, it automatically makes a copy of the existing database. If the restore fails, the database, Local Folders, settings and credentials return to their previous state.

If the backup comes from another computer, YouniqMail asks for that computer’s recovery key, because the database in the backup is encrypted with the old computer’s key. The credentials of your accounts cannot be carried from one computer to another: after the restore, YouniqMail tells you that you need to enter the passwords again. Under Settings → Email Accounts these accounts are marked “Sign-in missing”. For IMAP and Gmail accounts, enter the password again with Enter password, for Gmail an app password. Microsoft accounts are signed in again with Sign in again. The accounts keep their emails, folders and settings.

YouniqMail never carries over the sign-ins to connected services when restoring, not even on the same computer. After the restart you connect Trello, Todoist, Asana, Jira, Notion, Teams and Zoom again under Settings → Integrations. For CalDAV accounts you enter the password again, for webhooks the URL and your own headers. All other settings of the services are kept, and after the restore YouniqMail tells you which services are affected.

A backup from YouniqMail 0.9.5 or newer also holds the Local Folders. Only restore it with 0.9.5 or a newer version; older versions do not know the format. Older backups still restore in every version.

Taking out single Local Folders

To take only some Local Folders along, for example into another mail program, export them via File → Export as mbox or as .eml files. If the app no longer starts, the emergency program from Opening Local Folders without the app helps.

The backup replaces everything

Restoring overwrites the existing database, it does not merge. On a device where you already work with YouniqMail, all local data is lost in the process.

Transferring settings only

To carry your settings to a second device without hauling the mail along, there is a leaner path.

On the same page you find Export settings with Export now. The resulting JSON file contains only your application settings and the master password hint, no emails, no contacts and no credentials. Accounts therefore need to be set up anew on the target device. The file is read in under Import settings with Import from file.

Moving to a new machine

The comfortable way:

1. Create a full backup on the old device and keep the old device’s recovery key at hand.
2. Install and launch YouniqMail on the new one.
3. Complete the setup wizard.
4. Restore the backup and enter the old device’s recovery key when YouniqMail asks for it.
5. After the restart, sign the marked accounts in again under Settings → Email Accounts: enter the password or app password again for IMAP and Gmail accounts, and choose Sign in again for Microsoft accounts.

The backup brings its encryption along: if the database was encrypted on the old device, it is encrypted on the new one too, with the same recovery key.

The lean way, if a fresh start suits you anyway:

1. Export the settings.
2. Install on the new device, import the settings.
3. Set up the accounts again. The emails load from the server.

The lean way leaves notes, rules, contacts, signatures, templates, smart folders, keys and Local Folders behind. Tags and flags come back because they live on the server, but the tag colors do not.

Where the data lives

If you prefer backing up yourself, say with your usual backup tool:

Operating system:macOSWindowsLinux

~/Library/Application Support/YouniqMail/

%APPDATA%\YouniqMail\

~/.config/YouniqMail/

Copy only while the app is closed

The database consists of several files that belong together (mails, mails-wal, mails-shm). Copy them while the app is running, and the copy may be unusable. Quit YouniqMail completely first, or use the built-in backup, which takes care of this itself. Always copy the whole folder: next to the database, config.json with settings and credentials and the local_mail folder with your Local Folders belong to it.

The recovery key

If your database is encrypted (which is the default), a file copy is useless on a foreign device. The key is sealed with the help of your operating system and can only be opened there.

For exactly this case there is the recovery key. You saw it during first-run setup. YouniqMail asks for it when you restore a full backup from another device.

You can display it again under Settings → Security → Encrypt Storage. It can also be saved as a PDF there. On a Mac with Touch ID, you confirm that with your fingerprint.

No key, no recovery

If both the sealed key and the recovery key are lost, the database can no longer be read. That is not a setting or a lock that can be bypassed. It is the consequence of real encryption. Keep the key separate from your backups.

How often to back up?

That depends on how much local work lives in your mailbox. If you barely use notes and rules, a backup before major changes is enough. If you work heavily with follow-ups, notes and automations, a monthly backup is a good rhythm.

Remember: the emails themselves can be fetched from the server at any time. The backup is about everything else.