Imapc Configuration

See Imapc for a technical description of Dovecot’s imapc mailbox format.

Mail Location Configuration Examples

# In-memory index files:
mail_location = imapc:

# Store index files locally:
mail_location = imapc:~/imapc

Connection Settings

imapc_cmd_timeout

  • Default: 5 mins

  • Values: Time

How long to wait for a reply to an IMAP command sent to the remote IMAP server before disconnecting and retrying.

imapc_connection_retry_count

How many times to retry connection against a remote IMAP server?

imapc_connection_retry_interval

How long to wait between retries against a remote IMAP server?

imapc_features

  • Default: <empty>

  • Values: String

A space-separated list of features, optimizations, and workarounds that can be enabled.

Features

acl

When this feature is enabled and the imap-acl plugin is loaded, using a remote location via imapc will make IMAP ACL commands (MYRIGHTS, GETACL, SETACL, DELETEACL) proxied to the remote.

New in version 2.3.15.

delay-login

Don’t connect to the remote server until some command requires it. By default the server is connected to immediately on login.

New in version v2.2.29.

gmail-migration

Enable GMail-specific migration. Use IMAP X-GM-MSGID as POP3 UIDL. Add $GMailHaveLabels keyword to mails that have X-GM-LABELS except for \Muted keyword (to be used for migrating only archived emails in All Mails). Add pop3_deleted_flag to mails that don’t exist in POP3 server.

modseq

Access MODSEQ and HIGHESTMODSEQ

New in version 2.2.24.

proxyauth

Use Sun/Oracle IMAP-server specific PROXYAUTH command to do master user authentication. Normally this would be done using the SASL PLAIN authentication.

throttle:<INIT>:<MAX>:<SHRINK>

When receiving [THROTTLED] response (from GMail), throttling is applied.

INIT = initial throttling msecs (default: 50 ms), afterwards each subsequent [THROTTLED] doubles the throttling until MAX is reached (default: 16000 ms). When [THROTTLED] is not received for a while, it’s shrank again. The initial shrinking is done after SHRINK (default: 500 ms). If [THROTTLED] is received again within this timeout, it’s doubled, otherwise both throttling and the next shrinking timeout is shrank to 3/4 the previous value.

Optimizations

fetch-bodystructure

Allow fetching BODY and BODYSTRUCTURE FETCH BODY.PEEK[HEADER.FIELDS (..)].

fetch-headers

Allow fetching specific message headers from remote server.

New in version 2.2.30.

rfc822.size

Allow passing through message sizes using FETCH RFC822.SIZE.

search

Allow using SEARCH command.

Workarounds

fetch-fix-broken-mails

If a FETCH returns NO (but not NO [LIMIT] or NO [SERVERBUG]), assume the mail is broken in server and just treat it as if it were an empty email.

Warning

This is often a dangerous option! It’s not safe to assume that NO means a permanent error rather than a temporary error. This feature should be enabled only for specific users who have been determined to be broken.

fetch-msn-workarounds

Try to ignore wrong message sequence numbers in FETCH replies whenever possible, preferring to use the returned UID number instead.

no-examine

Use SELECT instead of EXAMINE even when we don’t want to modify anything in the mailbox. This is a Courier-workaround where it didn’t permanently assign UIDVALIDITY to an EXAMINEd mailbox, but assigned it for SELECTed mailbox.

no-qresync

Disable the QRESYNC extension even if advertised by the IMAP server. This can be used to work around a Zimbra bug where it doesn’t send untagged OK [CLOSED] imap-resp-code when selecting a folder.

New in version 2.3.22.

zimbra-workarounds

Fetch full message using BODY.PEEK[HEADER] BODY.PEEK[TEXT] instead of just BODY.PEEK[] because the header differs between these two when there are illegal control chars or 8bit chars. This mainly caused problems with dsync, but as of v2.2.22+ this should no longer be a problem and there’s probably no need to enable this workaround.

imapc_host

  • Default: <empty>

  • Values: String

The remote IMAP host to connect to.

imapc_list_prefix

  • Default: <empty>

  • Values: String

Access only mailboxes under this prefix.

Example, for a source IMAP server that uses an INBOX namespace prefix:

imapc_list_prefix = INBOX/
imapc_master_user

  • Default: <empty>

  • Values: String

The master username to authenticate as on the remote IMAP host.

To authenticate as a master user but use a separate login user, the following configuration should be employed, where the credentials are represented by masteruser and masteruser-secret:

imapc_user = %u
imapc_master_user = masteruser
imapc_password = masteruser-secret

Mail user variables can be used.

See also

imapc_password

imapc_user

imapc_max_idle_time

  • Default: 29 mins

  • Values: Time

Send a command to the source IMAP server as a keepalive after no other command has been sent for this amount of time.

Dovecot will send either NOOP or DONE to the source IMAP server.

imapc_max_line_length

  • Default: 0

  • Values: Size

The maximum line length to accept from the remote IMAP server.

This setting is used to limit maximum memory usage.

A value of 0 indicates no maximum.

imapc_password

  • Default: <empty>

  • Values: String

The authentication password for the remote IMAP server.

If using master users, this setting will be the password of the master user.

See also

imapc_master_user

imapc_user

imapc_port

The port on the remote IMAP host to connect to.

imapc_rawlog_dir

  • Default: <empty>

  • Values: String

Log all IMAP traffic input/output to this directory.

See also

Rawlog

imapc_sasl_mechanisms

  • Default: plain

  • Values: String

The SASL mechanisms to use for authentication when connection to a remote IMAP server.

The first one advertised by the remote IMAP sever is used.

Example:

imapc_sasl_mechanisms = external plain login
imapc_ssl

  • Default: no

  • Values: no, imaps, starttls

Use TLS to connect to the remote IMAP server.

Value

Description

no

No TLS

imaps

Explicitly connect to remote IMAP port using TLS

starttls

Use IMAP STARTTLS command to switch to TLS connection
imapc_ssl_verify

Verify remote IMAP TLS certificate?

Verification may be disabled during testing, but should be enabled during production use.

Only used if imapc_ssl is enabled.

See also

imapc_ssl

imapc_user

  • Default: <empty>

  • Values: String

The user identity to be used for performing a regular IMAP LOGIN to the source IMAP server.

Mail user variables can be used.

See also

imapc_master_user

imapc_password

Usage Examples

Do a regular IMAP LOGIN, using STARTTLS, to imap.example.com:

imapc_host = imap.example.com
imapc_password = secret
imapc_port = 143
imapc_ssl = starttls
imapc_user = user@example.com

Quota

Using the imapc quota backend allows asking for the quota from remote IMAP server (v2.2.30+). By default it uses GETQUOTAROOT INBOX to retrieve the quota.

There are two parameters that can be used to control how the quota is looked up:

  • box = <mailbox>: Use GETQUOTAROOT <mailbox>

  • root = <name>: Use GETQUOTA <name>

Example:

plugin {
  quota = imapc:root=User Quota
}