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IMAP

IMAP (Internet Message Access Protocol) is a standard email protocol used by mail clients to retrieve messages from a mail server over TCP/IP. The IMAP integration includes two connectors:

Connector type Description
Source connector Back up mailbox contents from an IMAP server into a Kloset store.
Destination connector Restore mailbox snapshots to an IMAP server.

Requirements

  • An IMAP account with read access for backup, and write access for restore.

Typical use cases

  • Long-term archival and audit of email hosted on IMAP servers, including folders, metadata, and attachments.
  • Restoring mailbox snapshots to any compatible IMAP destination, preserving folder structure and message integrity.
  • Backing up a single mailbox (and its sub-mailboxes) rather than an entire account.

Compatibility

  • Works with standard IMAP servers, including self-hosted and enterprise environments. Verified end-to-end against Dovecot.

Installation

The IMAP integration is distributed as a Plakar package.

Pre-compiled packages are available for common platforms and provide the simplest installation method.

Logging In

Pre-built packages require Plakar authentication. See Logging in to Plakar for details.

Install the IMAP package:

$ plakar pkg add imap

Verify installation:

$ plakar pkg list

Source builds are useful when pre-built packages are unavailable or when customization is required.

Prerequisites:

  • Go toolchain compatible with your Plakar version

Build the package:

$ plakar pkg build imap

A package archive will be created in the current directory (e.g., imap_v1.0.0_darwin_arm64.ptar).

Install the package:

$ plakar pkg add ./imap_v1.0.0_darwin_arm64.ptar

Verify installation:

$ plakar pkg list

To list, upgrade, or remove the package, see managing packages guide.

Connectors

The IMAP package provides two connectors: a source connector for backing up mailbox contents over IMAP, and a destination connector for restoring mailbox snapshots over IMAP.

Source connector

The Plakar IMAP package provides a source connector to back up mailbox contents reachable over IMAP.

flowchart LR

subgraph Source["IMAP Server"]
  FS["Mailbox"]
end

Plakar["Plakar"]

Via["Retrieve messages via
IMAP source connector"]

Store["Kloset Store"]

FS --> Via --> Plakar --> Store

Configure 

# Configure an IMAP source connector
$ plakar source add myIMAPsrc imap://imap.mydomain.com:143 \
  username=myuser \
  password=mypassword \
  tls=starttls

# Back up the mailbox
$ plakar at /var/backups backup "@myIMAPsrc"

# Back up only a specific folder (and its sub-folders)
$ plakar source add myArchive imap://imap.mydomain.com/Archive \
  username=myuser password=mypassword tls=starttls
$ plakar at /var/backups backup "@myArchive"

Options

These options can be set when configuring the source connector with plakar source add or plakar source set:

Option Description
location imap://[user[:password]@]host[:port][/mailbox]. Port defaults to 993 for TLS and 143 otherwise. An optional trailing path scopes the backup to a single mailbox and its sub-mailboxes, e.g. imap://host/Archive backs up Archive and everything nested under it, leaving the rest of the account untouched. Nested folders use / regardless of the server’s hierarchy delimiter, and a mailbox name containing / must be percent-encoded (%2F).
username Username to log in with. Overrides the URI user.
password Password to log in with. Overrides the URI password.
tls TLS mode: starttls (default), tls, or no-tls.
tls_no_verify Skip server certificate verification when true. Dangerous; testing only.
io_timeout Idle timeout for each IMAP socket operation, as a Go duration (e.g. 2m, 30s). Defaults to 2m. A stalled or failed message-body fetch is retried once on a fresh connection before being recorded as a per-message error, so a transient throttle is recovered transparently.

Destination connector

The Plakar IMAP package provides a destination connector to restore mailbox snapshots to an IMAP server.

flowchart LR

Store["Kloset Store"]

Plakar["Plakar"]

Via["Push messages via
IMAP destination connector"]

subgraph Destination["IMAP Server"]
  FS["Mailbox"]
end

Store --> Plakar --> Via --> FS

Configure 

# Configure an IMAP destination connector
$ plakar destination add myIMAPdst imap://imap.alsomydomain.com:143 \
  username=alsomyuser password=alsomypassword tls=starttls

# Restore the snapshot to the destination
$ plakar at /var/backups restore -to "@myIMAPdst" <snapshot_id>

Options

These options can be set when configuring the destination connector with plakar destination add or plakar destination set:

Option Description
location imap://[user[:password]@]host[:port]. Port defaults to 993 for TLS and 143 otherwise. Any trailing mailbox path is ignored by the destination connector; restored mailboxes are recreated according to the snapshot.
username Username to log in with. Overrides the URI user.
password Password to log in with. Overrides the URI password.
tls TLS mode: starttls (default), tls, or no-tls.
tls_no_verify Skip server certificate verification when true. Dangerous; testing only.
io_timeout Idle timeout for each IMAP socket operation, as a Go duration (e.g. 2m, 30s). Defaults to 2m.

Behavior

  • Folder hierarchy is preserved across servers even when source and destination use different hierarchy delimiters (for example Dovecot’s . vs /). Each mailbox segment is percent-encoded into the snapshot path, so a folder named Work/Notes or Reçus round-trips intact.
  • Message flags (\Seen, \Answered, \Flagged, \Draft, \Deleted, and keywords such as $Junk) are encoded into each message’s file name and re-applied on restore. The session-only \Recent flag is intentionally dropped.
  • Messages are fetched with BODY.PEEK, so a backup never alters the source mailbox.
  • On restore, missing mailboxes (and their parents) are created automatically.

Limitations and scope

What is captured during backup

  • Messages within the scoped mailbox (or the entire account when no mailbox path is given), including folder structure and flags.

What is not captured

  • Server-side configuration outside the mailbox contents (e.g., server settings, ACLs)
  • The session-only \Recent flag

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