jmap-backup-rs-0.1.0 is not a library.

jmap-backup-rs

Backup email from a JMAP account to local .eml files.

jmap-backup-rs connects to a JMAP server, queries email, downloads each message as a raw blob, and stores it under a date-based folder layout:

emails/
  2026/
    06/
      02/
        <email-id>.eml

Existing files are skipped, so repeated runs can be used to incrementally update the backup directory.

Status

This is an early release. It currently targets Fastmail-friendly defaults and backs up mail only. Restore, delete detection, mailbox metadata, labels, and contacts are not implemented.

Installation

Install from source with Cargo:

cargo install --git https://git.thaller.ws/athaller/jmap-backup-rs

Or clone the repository and build locally:

git clone https://git.thaller.ws/athaller/jmap-backup-rs.git
cd jmap-backup-rs
cargo build --release

The optimized binary will be available at target/release/jmap-backup-rs.

Usage

Create a JMAP API token with permission to read mail, then pass it with JMAP_TOKEN:

export JMAP_TOKEN='your-token-here'
cargo run --release -- --backup-folder emails

Fastmail is the default endpoint:

https://api.fastmail.com

For a different JMAP service, provide the endpoint explicitly:

jmap-backup-rs \
  --url https://jmap.example.com \
  --redirect-host jmap.example.com \
  --backup-folder emails

Command-line options:

-b, --backup-folder <PATH>       Path to the backup folder [default: emails]
-t, --token <TOKEN>              JMAP bearer token [env: JMAP_TOKEN]
    --url <URL>                  JMAP API endpoint [env: JMAP_URL]
    --redirect-host <HOST>       Hosts that redirects may follow [env: JMAP_REDIRECT_HOST]
                                 [default: api.fastmail.com]
-h, --help                       Print help
-V, --version                    Print version

Backup Format

Messages are written as .eml files using the message receive date:

<backup-folder>/<year>/<month>/<day>/<email-id>.eml

The tool checks for existing filenames before downloading, which keeps reruns cheap when the backup already contains messages.

Security Notes

Keep your JMAP token private. Prefer the JMAP_TOKEN environment variable over putting tokens directly in shell history, and revoke the token if it is ever committed or shared accidentally.

Backups contain the full raw email content, including headers, addresses, message bodies, and attachments. Store the backup directory somewhere private, and encrypt it when appropriate.

Development

Run the formatter and checks before opening a pull request:

cargo fmt
cargo clippy --all-targets --all-features
cargo test

Build a smaller optimized release binary with the custom deploy profile:

cargo build --profile deploy

License

MIT. See LICENSE.

jmap-backup-rs 0.1.0