I am using the trees[1] plugin to encrypt the mail on my disk. Because I don't want it to store any metadata in plaintext, I've also set INDEX=MEMORY in my mail_location configuration.

However, whenever I get new mail I get errors like the following showing up in the journal:

lmtp(john@octet.space)<21780><QDkrBqTXclwUVQAAQHGRUQ>: Error: Mailbox INBOX: Saving mail: read(/var/vmail/octet.space/john/Maildir/tmp/1551030180.M508113P21780.toaster.octet.space) failed: Permission denied (read reason=header Subject (Cache file is unusable))

It's like it's trying to read the message after it's been delivered, but is not able to because it's been encrypted. I seem to be able to get email just fine despite the error message. This happens both if I deliver mail using dovecot-lda or lmtp.

Is there any way to fix this or at the very least suppress the error message? I have included my dovecot configuration below.

[1] https://0xacab.org/riseuplabs/trees

[root@toaster ~]# dovecot --version 2.3.4.1 (f79e8e7e4) [root@toaster ~]# dovecot -n # 2.3.4.1 (f79e8e7e4): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.4 (60b0f48d) # OS: Linux 4.20.8-arch1-1-ARCH x86_64 ext4 # Hostname: toaster.octet.space base_dir = /run/dovecot/ hostname = toaster.octet.space mail_gid = vmail mail_home = /var/vmail/%d/%n mail_location = maildir:/var/vmail/%d/%n/Maildir:UTF-8:INDEX=MEMORY mail_plugins = " quota trash zlib trees notify replication" mail_privileged_group = vmail mail_uid = vmail mailbox_list_index_very_dirty_syncs = yes 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 spamtest spamtestplus imapflags notify imapsieve vnd.dovecot.imapsieve namespace inbox { inbox = yes location = maildir:/var/vmail/%d/%n/Maildir:UTF-8:INDEX=MEMORY mailbox Drafts { auto = create special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { auto = subscribe special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Spam { auto = create autoexpunge = 30 days special_use = \Junk } mailbox Trash { special_use = \Trash } prefix = } passdb { args = /etc/dovecot/dovecot-sql.conf.ext driver = sql } plugin { imapsieve_mailbox1_before = file:/var/lib/dovecot/imapsieve/before/report-spam.sieve imapsieve_mailbox1_causes = COPY FLAG imapsieve_mailbox1_name = Spam imapsieve_mailbox2_before = file:/var/lib/dovecot/imapsieve/before/report-ham.sieve imapsieve_mailbox2_causes = COPY imapsieve_mailbox2_from = Spam imapsieve_mailbox2_name = * quota = maildir:User quota quota_max_mail_size = 100M quota_rule = *:storage=15G quota_warning = storage=95%% quota-warning 95 %u quota_warning2 = storage=80%% quota-warning 80 %u quota_warning3 = -storage=100%% quota-warning below %u recipient_delimiter = + sieve = file:~/sieve;active=~/.dovecot.sieve sieve_before = /var/lib/dovecot/sieve/before/ sieve_extensions = +spamtest +spamtestplus +notify +imapflags sieve_filter_socket_dir = sieve-pipe sieve_global_extensions = +vnd.dovecot.pipe +vnd.dovecot.environment +vnd.dovecot.filter sieve_pipe_socket_dir = sieve-pipe sieve_plugins = sieve_imapsieve sieve_extprograms sieve_quota_max_storage = 4M sieve_spamtest_max_header = X-Spam-Score: -?[[:digit:]]+\.[[:digit:]]+ / (-?[[:digit:]]+\.[[:digit:]]) sieve_spamtest_status_header = X-Spam-Score: (-?[[:digit:]]+\.[[:digit:]]+) / -?[[:digit:]]+\.[[:digit:]] sieve_spamtest_status_type = score trash = /etc/dovecot/dovecot-trash.conf.ext zlib_save = xz zlib_save_level = 6 } protocols = imap lmtp service auth-worker { group = smtpd user = $default_internal_user } service auth { unix_listener auth-userdb { group = vmail mode = 0660 user = vmail } } service dovecot-lda { executable = script /usr/lib/dovecot/dovecot-lda.sh unix_listener sieve-pipe/dovecot-lda { mode = 0600 user = vmail } user = vmail } service filter_rspamc { executable = script /usr/lib/dovecot/filter_rspamc.sh group = vmail unix_listener sieve-pipe/filter_rspamc { mode = 0600 user = vmail } user = vmail } service imap-login { inet_listener imap { port = 0 } inet_listener imaps { port = 993 ssl = yes } } service learn_ham { executable = script /usr/lib/dovecot/learn_ham.sh group = vmail unix_listener sieve-pipe/learn_ham { mode = 0600 user = vmail } user = vmail } service learn_spam { executable = script /usr/lib/dovecot/learn_spam.sh group = vmail unix_listener sieve-pipe/learn_spam { mode = 0600 user = vmail } user = vmail } service lmtp { unix_listener lmtp { group = vmail mode = 0660 user = vmail } } service pop3-login { inet_listener pop3 { port = 0 } inet_listener pop3s { port = 0 } } service quota-warning { executable = script /usr/lib/dovecot/quota-warning.sh unix_listener quota-warning { group = vmail mode = 0660 user = vmail } user = vmail } ssl = required ssl_cert = </etc/acme/fullchain.cer ssl_cipher_list = TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256 ssl_key = # hidden, use -P to show it ssl_min_protocol = TLSv1.2 ssl_prefer_server_ciphers = yes userdb { driver = prefetch } userdb { args = /etc/dovecot/dovecot-sql.conf.ext driver = sql } protocol lda { mail_plugins = " quota trash zlib trees notify replication sieve zlib" } protocol imap { mail_plugins = " quota trash zlib trees notify replication imap_quota imap_sieve imap_zlib zlib" } protocol lmtp { mail_plugins = " quota trash zlib trees notify replication sieve zlib" }