Update dovecot config files to bullseye, mostly adding comments

mail_system/templates/dovecot/10-auth.conf

@@ -13,7 +13,7 @@
 #disable_plaintext_auth = yes
 
 # Authentication cache size (e.g. 10M). 0 means it's disabled. Note that
-# bsdauth, PAM and vpopmail require cache_key to be set for caching to be used.
+# bsdauth and PAM require cache_key to be set for caching to be used.
 #auth_cache_size = 0
 # Time to live for cached data. After TTL expires the cached record is no
 # longer used, *except* if the main database lookup returns internal failure.
@@ -98,7 +98,7 @@ auth_default_realm = {{ mailserver.dovecot.auth_default_realm }}
 #auth_ssl_username_from_cert = no
 
 # Space separated list of wanted authentication mechanisms:
-#   plain login digest-md5 cram-md5 ntlm rpa apop anonymous gssapi otp skey
+#   plain login digest-md5 cram-md5 ntlm rpa apop anonymous gssapi otp
 #   gss-spnego
 # NOTE: See also disable_plaintext_auth setting.
 auth_mechanisms = plain login
@@ -128,6 +128,4 @@ auth_mechanisms = plain login
 #!include auth-ldap.conf.ext
 #!include auth-passwdfile.conf.ext
 #!include auth-checkpassword.conf.ext
-#!include auth-vpopmail.conf.ext
 #!include auth-static.conf.ext
-

mail_system/templates/dovecot/10-mail.conf

@@ -452,10 +452,10 @@ protocol !indexer-worker {
 # Settings to control adding $HasAttachment or $HasNoAttachment keywords.
 # By default, all MIME parts with Content-Disposition=attachment, or inlines
 # with filename parameter are consired attachments.
-#   add-flags-on-save - Add the keywords when saving new mails.
+#   add-flags - Add the keywords when saving new mails or when fetching can
+#      do it efficiently.
 #   content-type=type or !type - Include/exclude content type. Excluding will
 #     never consider the matched MIME part as attachment. Including will only
 #     negate an exclusion (e.g. content-type=!foo/* content-type=foo/bar).
 #   exclude-inlined - Exclude any Content-Disposition=inline MIME part.
 #mail_attachment_detection_options =
-

mail_system/templates/dovecot/10-ssl.conf

@@ -33,10 +33,15 @@ ssl_key = </etc/dovecot/private/dovecot.key
 # when Dovecot needs to act as an SSL client (e.g. imapc backend or
 # submission service). The directory is usually /etc/ssl/certs in
 # Debian-based systems and the file is /etc/pki/tls/cert.pem in
-# RedHat-based systems.
+# RedHat-based systems. Note that ssl_client_ca_file isn't recommended with
+# large CA bundles, because it leads to excessive memory usage.
+#ssl_client_ca_dir =
 ssl_client_ca_dir = /etc/ssl/certs
 #ssl_client_ca_file =
 
+# Require valid cert when connecting to a remote server
+#ssl_client_require_valid_cert = yes
+
 # Request client to send a certificate. If you also want to require it, set
 # auth_ssl_require_client_cert=yes in auth section.
 #ssl_verify_client_cert = no
@@ -54,6 +59,7 @@ ssl_dh = </usr/share/dovecot/dh.pem
 
 # Minimum SSL protocol version to use. Potentially recognized values are SSLv3,
 # TLSv1, TLSv1.1, and TLSv1.2, depending on the OpenSSL version used.
+#ssl_min_protocol = TLSv1
 ssl_min_protocol = TLSv1.2
 
 # SSL ciphers to use, the default is:
@@ -76,4 +82,3 @@ ssl_min_protocol = TLSv1.2
 #   compression - Enable compression.
 #   no_ticket - Disable SSL session tickets.
 #ssl_options =
-

mail_system/templates/dovecot/15-mailboxes.conf

@@ -31,6 +31,8 @@
 #     \Drafts    - This mailbox is used to hold draft messages.
 #     \Flagged   - This (virtual) mailbox presents all messages in the
 #                  user's message store marked with the IMAP \Flagged flag.
+#     \Important - This (virtual) mailbox presents all messages in the
+#                  user's message store deemed important to user.
 #     \Junk      - This mailbox is where messages deemed to be junk mail
 #                  are held.
 #     \Sent      - This mailbox is used to hold copies of messages that
@@ -82,5 +84,10 @@ namespace inbox {
   #  special_use = \Flagged
   #  comment = All my flagged messages
   #}
-}
 
+  # If you have a virtual "Important" mailbox:
+  #mailbox virtual/Important {
+  #  special_use = \Important
+  #  comment = All my important messages
+  #}
+}

mail_system/templates/dovecot/20-imap.conf

@@ -46,7 +46,8 @@
 
 # ID field names and values to send to clients. Using * as the value makes
 # Dovecot use the default value. The following fields have default values
-# currently: name, version, os, os-version, support-url, support-email.
+# currently: name, version, os, os-version, support-url, support-email,
+# revision.
 #imap_id_send = 
 
 # ID fields sent by client to log. * means everything.
@@ -93,10 +94,10 @@
 
 protocol imap {
   # Space separated list of plugins to load (default is global mail_plugins).
+  #mail_plugins = $mail_plugins
   mail_plugins = $mail_plugins imap_sieve imap_acl imap_quota
 
   # Maximum number of IMAP connections allowed for a user from each IP address.
   # NOTE: The username is compared case-sensitively.
   #mail_max_userip_connections = 10
 }
-

mail_system/templates/dovecot/20-lmtp.conf

@@ -16,6 +16,9 @@
 # Verify quota before replying to RCPT TO. This adds a small overhead.
 #lmtp_rcpt_check_quota = no
 
+# Add "Received:" header to mails delivered.
+#lmtp_add_received_header = yes
+
 # Which recipient address to use for Delivered-To: header and Received:
 # header. The default is "final", which is the same as the one given to
 # RCPT TO command. "original" uses the address given in RCPT TO's ORCPT
@@ -23,6 +26,17 @@
 # when a mail has multiple recipients.
 #lmtp_hdr_delivery_address = final
 
+# Workarounds for various client bugs:
+#   whitespace-before-path:
+#     Allow one or more spaces or tabs between `MAIL FROM:' and path and between
+#     `RCPT TO:' and path.
+#   mailbox-for-path:
+#     Allow using bare Mailbox syntax (i.e., without <...>) instead of full path
+#     syntax.
+#
+# The list is space-separated.
+#lmtp_client_workarounds =
+
 protocol lmtp {
   # Space separated list of plugins to load (default is global mail_plugins).
   #mail_plugins = $mail_plugins

mail_system/templates/dovecot/90-quota.conf

@@ -90,7 +90,7 @@ plugin {
   quota_grace = 10%%
   quota_status_success = DUNNO
   quota_status_nouser = DUNNO
-  quota_status_overquota = "452 4.2.2 Mailbox is full and cannot receive any more emails"
+  quota_status_overquota = "552 5.2.2 Mailbox is full"
   quota_exceeded_message = Quota exceeded, please reduce your overall mail volume and/or the number of messages in your inbox.
 
   # https://wiki2.dovecot.org/Quota/Configuration