Upgrading Dovecot CE from 2.4 to 2.4.x

Dovecot CE

v2.4.0 to v2.4.1

• Added MALLOC_MMAP_THRESHOLD_=131072 to import_environment when building with glibc. Note that dovecot_config_version value does not affect change - it's always added.

v2.4.2 to v2.4.3

• Using Settings Variables with LDAP settings now requires using | safe filter to allow passing through LDAP characters that are otherwise escaped. The safe filter must always be the last filter in the pipeline. Note that this should be used only for variables coming from trusted sources, not for e.g. username variable.

Changed Setting Defaults

These changes don't take effect until dovecot_config_version is changed from 2.4.0 to 2.4.1.

Setting	Old Default Value	New Default Value
mail_cache_fields	flags	flags hdr.date hdr.subject hdr.from hdr.sender hdr.reply-to hdr.to hdr.cc hdr.bcc hdr.in-reply-to hdr.message-id date.received size.virtual imap.bodystructure mime.parts hdr.references hdr.importance hdr.x-priority hdr.x-open-xchange-share-url pop3.uidl pop3.order
service/auth/unix_listener/auth-userdb/group	(empty = root)	$SET:default_internal_group
service/lmtp/restart_request_count	unlimited	1
lmtp_user_concurrency_limit	unlimited	10

v2.4.1 to v2.4.2

Changed Setting Defaults

These changes don't take effect until dovecot_config_version is changed to 2.4.2.

Setting	Old Default Value	New Default Value
@metric_defaults/proxy/metric		Adds proxy_session_established
service/anvil/unix_listener/anvil/mode	0600	0660
service/anvil/unix_listener/anvil/group	(empty = root)	$SET:default_internal_group
mailbox_directory_name_legacy	yes	no
mail_attachment_detection_options		add-flags content-type=!application/signature

v2.4.2 to v2.4.3

Changed Setting Defaults

These changes don't take effect until dovecot_config_version is changed to 2.4.3.

Setting	Old Default Value	New Default Value
fts_message_max_size		0 is not allowed anymore to mean unlimited use unlimited instead
last_valid_gid		0 is not allowed anymore to mean unlimited use unlimited instead
last_valid_uid		0 is not allowed anymore to mean unlimited use unlimited instead
lazy_expunge_only_last_instance	no	yes
mail_access_groups		default_internal_group
mail_cache_max_header_name_length		0 is not allowed anymore to mean unlimited use unlimited instead
mail_cache_max_headers_count		0 is not allowed anymore to mean unlimited use unlimited instead
mail_sort_max_read_count		0 is not allowed anymore to mean unlimited use unlimited instead
mail_vsize_bg_after_count		0 is not allowed anymore to mean unlimited use unlimited instead
passdb_default_password_scheme	PLAIN	CRYPT
sieve_quota_script_count		0 is not allowed anymore to mean unlimited use unlimited instead
sieve_quota_storage_size		0 is not allowed anymore to mean unlimited use unlimited instead
submission_max_recipients		0 is not allowed anymore to mean unlimited use unlimited instead
maildir/mail_attachment_detection_options	add-flags content-type=!application/signature
passdb_passwd_file/passdb_default_password_scheme	PLAIN	CRYPT
passdb_sql/passdb_default_password_scheme	PLAIN	CRYPT
service/doveadm/service_extra_groups	default_internal_group
service/imap/service_extra_groups	default_internal_group
service/imap-urlauth-worker/service_extra_groups	default_internal_group
service/indexer-worker/service_extra_groups	default_internal_group
service/lmtp/service_extra_groups	default_internal_group
service/pop3/service_extra_groups	default_internal_group
service/submission/service_extra_groups	default_internal_group
service/managesieve/service_extra_groups	default_internal_group
@mailbox_defaults/english/namespace/inbox/mailbox/Drafts/mailbox_auto	no	subscribe
@mailbox_defaults/english/namespace/inbox/mailbox/Junk/mailbox_auto	no	subscribe
@mailbox_defaults/english/namespace/inbox/mailbox/Sent/mailbox_auto	no	subscribe
@mailbox_defaults/english/namespace/inbox/mailbox/Trash/mailbox_auto	no	subscribe
service/anvil/unix_listener/anvil-auth-penalty/mode	0600	0660
service/anvil/unix_listener/anvil-auth-penalty/group		default_internal_group
service/imap/unix_listener/imap-master/user		default_internal_user

Removed Features

Feature	Notes
acl_global_path setting	See ACL Settings Migration.

v2.4.3 to v2.4.4

Forcibly Changed Setting Defaults

Unlike other default setting changes, this change takes effect regardless of dovecot_config_version. This is because indexer-worker now drops root privileges, and the old default could make the service non-working.

Setting	Old Default Value	New Default Value
service/indexer-worker/service_restart_request_count	service_restart_request_count	1

Changed Setting Defaults

These changes don't take effect until dovecot_config_version is changed to 2.4.4.

Setting	Old Default Value	New Default Value
push_notification_ox/http_client_request_max_attempts	1	2
push_notification_ox/http_client_request_timeout	1min	2s
service/lmtp/service_extra_groups		default_internal_group

v2.4.4 to v2.4.5

• String List and Boolean List setting keys are now expanded with Settings variables the same way their values already were. Keys defined in the configuration are always expanded. For settings overrides only default overrides expand the keys; keys coming from -o command line parameters and from userdb are kept literal.
• The per-field time and date Settings Variables providers are now deprecated: time:hour, time:min, time:minute, time:sec, time:second, time:usec and date:year, date:month, date:day. Use the new time:unix provider together with the date filter instead. Note that the old providers always used the local timezone, whereas the date filter defaults to UTC, so to keep the old behavior pass tz='local': use %{time:unix | date('%H', 'local')} in place of %{time:hour}. The new approach additionally supports UTC, timestamps from any other variable, and ISO 8601 / RFC 3339 output via the iso8601 filter. The deprecated providers keep working for now.

Changed Setting Defaults

These changes don't take effect until dovecot_config_version is changed to 2.4.5.

Setting	Old Default Value	New Default Value
sieve_max_cpu_time	0 (unlimited)	30s
imap_compress_on_proxy	no	yes

Changed Storage Formats

These changes don't take effect until dovecot_storage_version is changed to 2.4.5.

The dovecot.index.thread index, used by the IMAP THREAD command, has a new v2 format. The Message-ID hashes stored in it are now calculated with a keyed hash using a random per-file key instead of CRC32. This prevents users from crafting Message-IDs whose hashes deliberately collide, which would otherwise slow down threading.

Existing v1 index files are deleted and rebuilt in the v2 format when the mailbox is next opened for threading, so the first THREAD command for a large mailbox can be slower than usual. Dovecot versions older than v2.4.5 don't understand the v2 format and rebuild the index in the v1 format again, so this setting should be increased only once a rollback to an older version is no longer possible.

New Features

Feature	Notes
`escape` filter	Explicitly apply the configured escape function within a variable expansion pipeline. Useful for partial escaping when combined with concat and safe.
`time:unix` provider	Returns the current time as a <seconds>.<nanoseconds> UNIX timestamp. Recommended replacement for the deprecated per-field time:/date: providers.
`epoch`	Convert and format UNIX timestamps (unit scaling, calendar formatting via strftime, and ISO 8601 / RFC 3339 output).

Removed Features

Feature	Notes
auth: SIGHUP, SIGUSR2	Use doveadm auth cache flush to flush the cache and doveadm auth cache status to inspect cache statistics instead.

Sieve

Cumulative CPU usage tracking for sieve_max_cpu_time is no longer kept inside each compiled Sieve binary (.svbin). It is now stored in a single file sieve-rusage at the root of the user's INBOX namespace.

v2.4.5 to v2.4.6

• A passdb lookup returning an empty password now fails authentication instead of allowing login with an empty password. Passdb entries intended to have no fixed password should return the nopasswordextra field (e.g. user:::::::nopassword=yes in a passwd-file) instead of an empty password field; any non-empty client password is then accepted.
• An empty client-supplied password is now always rejected before the passdb lookup, for all passdb drivers. Previously only LDAP auth binds rejected it. nopassword does not allow an empty client password either; only mechanisms that authenticate without a password (EXTERNAL via client certificate, OAuth2) are unaffected.
• The EXTERNAL SASL mechanism now treats the client certificate as the authentication and no longer verifies any passdb password. Existing client-certificate setups (e.g. passwd-file entries with an empty password field) keep working. Passdbs that verify the password themselves no longer reject EXTERNAL logins either: e.g. an LDAP auth bind passdb attempts no bind - the lookup succeeds without verifying anything and only provides the extra fields, since the certificate already authenticated the user. For EXTERNAL loginspassdb { skip = authenticated } passdbs are now skipped and skip = unauthenticated passdbs run; if all passdbs are skipped, the login fails.