What mccb does with your mailboxes

PST and OST files, Exchange on premises (EWS), Microsoft 365 (Graph), Google Workspace, IMAP, JMAP, CalDAV and CardDAV, and files: mbox, Maildir, EML, MSG, ICS and VCF.

IMAP, CalDAV, CardDAV, JMAP and Exchange (EWS or Graph). Not every source is also a target: Google, PST and files are read-only sources.

Tasks go where the target can hold them: Exchange, or a CalDAV calendar that accepts VTODO.

Exchange impersonation, Graph app-only and an IMAP master user reach every mailbox with one account of yours.

Mail is imported from the newest to the oldest, across all folders.

No file needed: IMAP to IMAP, or Exchange, Microsoft 365 and Google to any IMAP server, while people keep working.

Exchange inbox rules are converted to Sieve on a best-effort basis, and uploaded over ManageSieve or offered as a script.

Migrations, Files, Servers and Settings, in a side bar on a computer and a top bar on a phone. Nine languages.

Pick the provider (Gmail, Microsoft 365, iCloud, Fastmail, Infomaniak or any IMAP server) and the form fills itself, with what the provider asks for. Each server shows whether it is verified.

From: a file or a live server, configured and tested in place. To: the server and the mailbox.

Each mailbox shows its source, its destination and what to copy, marked ready or not, and a start button that says what is missing.

Every state is an icon and a word, never a colour alone. What needs you comes first in the list.

One file at a time by default, with the order of your choice. Reorder, pause, resume or cancel.

Large files upload in chunks, each one checked by SHA-256. Free space is checked first.

Copy files into a folder of the server with rsync or a mount, and the worker picks them up.

The server downloads the file itself over HTTP(S), SFTP or an S3-compatible service.

See accents and attachments before anything is written.

Connects, lists and counts, and writes nothing to any target. It warns about quota and oversized messages.

Map folders, exclude folders, and filter by date or maximum size, per server or per mailbox.

Allowed hours and a bandwidth limit per server.

Named batches with group actions and a queue order.

A last pass for new IMAP messages at cutover, and a comparison of source and target as CSV and in the report.

Add mailboxes one by one, or by CSV (email;password[;login]). The export never contains a password.

The mccb command uploads with resume, starts migrations and follows them, with no browser.

Tell you when uploads, analyses and migrations finish, through ntfy, a webhook or e-mail.

Live progress, log and JSON report per mailbox.

Pause, stop, crash or restart: a resume checks the server and never duplicates a message.

Every job and every PST analysis runs in its own subprocess, so a crash of the native PST library cannot take the worker down.

After the mail phase, each folder's message count is compared to what was sent, and a sample of messages is read back and compared by hash. Exchange targets are counted only.

Auto or manual tuning of message builders and IMAP connections, per server.

Stored encrypted. The application can decrypt them, so protect ./data and the SECRET_KEY.

Everything is in ./data, including secret.key: without it the stored mailbox passwords cannot be decrypted.

The Exchange, Microsoft 365 and Google connectors have been tested against simulated servers only. Try one mailbox with few items first.

Mail written through Graph gets the date of the import. IMAP with OAuth2 as target keeps it.

Graph mails every attendee of an event it creates. By default attendees are written as text in the body of the event. Organisers and responses are not kept on an Exchange target.

Microsoft 365 archives are not reachable. Move their content to the primary mailbox first.

Not implemented. Use CalDAV for the calendars of a JMAP provider.

Attachments of events and contact photos are not copied. Bodies of events, contacts and tasks are plain text.

A migration copies in one direction. A final resync, started by hand, adds what arrived since, but a change or a deletion at the source after its copy is not carried over.

A Maildir or a folder of messages must be zipped. A .msg is converted on a best-effort basis, without RTF-only bodies, embedded messages or OLE objects.

A single administrator: one shared password, no accounts or roles. API tokens do not expire, revoke them by hand.

SQLite on a local disk: a single host, no high availability, no NFS.

Encrypted or password-protected PSTs have no dedicated handling. They give errors or are marked invalid. Do not rely on it.

A corrupted PST can crash libpff. Affected items are skipped and reported, and past MAX_CHILD_CRASHES crashes the job fails.

Delivery is best effort: three attempts, then the message is dropped. A public ntfy topic can be read by anyone who knows its name.

Port 22362 speaks plain HTTP. Put mccb behind a reverse proxy and do not expose the port directly.

The published image is for linux/amd64 only.

Items with no charset information may decode imperfectly in some languages.

Results depend on the target IMAP, DAV, JMAP or Exchange server.