I’m trying to configure dovecot to use mailbox subfolders that look like both foo/bar on the IMAP client and the filesystem.

But the subfolders created all look like foo.bar, not foo/bar with a proper nesting structure.

This also happens when the folder ‘bar’ is moved into the folder ‘foo’—A new folder `foo.bar’ is created.

I believe that i’m following the configuration rules at https://wiki.dovecot.org/MailboxFormat/Maildir#Maildir_and_filesystems and https://wiki.dovecot.org/MailLocation/Maildir. This issue happens whether I set separator to its default, ‘.’, or ‘/’:

mail_location = mdbox:/private/var/mail/tld.hostname.mail/%Ln/mdbox:LAYOUT=fs namespace inbox { … separator = / … }

The IMAP client is macOS Mail.app version 14.0.

I’d greatly appreciate any help or pointers to fix this configuration issue.

dovecot -n

# 2.3.13 (): /opt/local/etc/dovecot/dovecot.conf # Pigeonhole version 0.5.13 () # OS: Darwin 20.4.0 x86_64 apfs # Hostname: mail.hostname.tld aps_topic = com.apple.mail.XServer.ffffffff-ffff-fff-ffffffffff auth_cache_size = 10 M auth_gssapi_hostname = $ALL auth_krb5_keytab = /opt/local/etc/dovecot/imap.keytab auth_mechanisms = plain gssapi auth_realms =mail.hostname.tld auth_socket_path = /opt/local/var/run/dovecot/auth-userdb auth_username_format = %Ln debug_log_path = /opt/local/var/log/mail/mail-debug.log disable_plaintext_auth = no first_valid_gid = 6 first_valid_uid = 6 imap_id_log = * imap_id_send = "name" * "version" * imap_idle_notify_interval = 29 mins imap_urlauth_submit_user = submit info_log_path = /opt/local/var/log/mail/mail-info.log last_valid_gid = 100 lda_mailbox_autocreate = yes log_path = /opt/local/var/log/mail/mail-err.log login_log_format_elements = user=<%u> method=%m rip=%r lip=%l mpid=%e %c mail_access_groups = mail mail_attachment_dir = /private/var/mail/tld.hostname.mail/attachments mail_attachment_fs = sis posix:mode=0666 mail_gid = mail mail_home = /private/var/mail/tld.hostname.mail mail_location = mdbox:/private/var/mail/tld.hostname.mail/%Ln/mdbox:LAYOUT=fs mail_log_prefix = "%s(pid %p user %u): " mail_plugins = quota zlib acl fts fts_solr fts_lucene mail_privileged_group = mail mail_uid = _dovecot managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext imapsieve vnd.dovecot.imapsieve mdbox_rotate_size = 200 M namespace inbox { inbox = yes location = mailbox Archive { auto = subscribe special_use = \Archive } mailbox Drafts { auto = subscribe special_use = \Drafts } mailbox Junk { auto = create special_use = \Junk } mailbox Notspam_train { auto = create special_use = \Junk } mailbox Sent { auto = subscribe special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Spam_train { auto = create special_use = \Junk } mailbox Trash { auto = create special_use = \Trash } prefix = separator = / } passdb { driver = pam name = pam } plugin { fts = solr fts_autoindex = yes fts_autoindex_exclude = \Junk fts_solr = url=http://127.0.0.1:8983/solr/dovecot/ imapsieve_mailbox1_before = file:/opt/local/etc/dovecot/sieve/report-spam.sieve imapsieve_mailbox1_causes = COPY APPEND imapsieve_mailbox1_name = Spam_train imapsieve_mailbox2_before = file:/opt/local/etc/dovecot/sieve/report-ham.sieve imapsieve_mailbox2_causes = COPY APPEND imapsieve_mailbox2_name = Notspam_train mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename mail_log_fields = uid box msgid from subject size flags quota_grace = 10%% quota_rule = *:storage=16G quota_rule2 = Trash:storage=+256M quota_warning = storage=100%% quota-exceeded %u quota_warning2 = storage=80%% quota-warning %u recipient_delimiter = + sieve = /private/var/mail/tld.hostname.mail/rules/%Ln/dovecot.sieve sieve_after = /opt/local/etc/dovecot/sieve-after.d sieve_before = /opt/local/etc/dovecot/sieve-before.d sieve_dir = /private/var/mail/tld.hostname.mail/rules/%Ln/%u sieve_global_extensions = +vnd.dovecot.pipe +vnd.dovecot.environment sieve_pipe_bin_dir = /opt/local/etc/dovecot/sieve sieve_plugins = sieve_imapsieve sieve_extprograms sieve_quota_max_storage = 50M } postmaster_address = postmaster@hostname.tld protocols = imap lmtp sieve quota_full_tempfail = yes sendmail_path = /opt/local/sbin/sendmail service auth-worker { group = mail user = root } service auth { extra_groups = _keytabusers idle_kill = 15 mins unix_listener /opt/local/var/spool/postfix/private/auth { group = mail mode = 0660 user = _postfix } } service dns-client { unix_listener dns-client { mode = 0600 } } service imap-login { inet_listener imap { address = 127.0.0.1, ::1 port = 143 } inet_listener imaps { port = 993 ssl = yes } process_min_avail = 6 service_count = 0 vsz_limit = 2 G } service imap { process_limit = 200 process_min_avail = 6 } service lmtp { unix_listener /opt/local/var/spool/postfix/private/dovecot-lmtp { group = mail mode = 0660 user = _postfix } } ssl = required ssl_ca =