What might cause messages delivered with dovecot-lda to be "invisible" to IMAP clients?

[Ben Johnson]

Hello!

I'm attempting to use dovecot-lda, and for whatever reason, messages
that I send with it are not visible in my IMAP client.

$ dovecot --version
2.2.22 (fe789d2)

(Full "doveconf -n" output is at the bottom of this message!)

Here's the the sequence of commands that I'm using:

# su vmail

$ echo 'This is a test message.' > /tmp/test.txt

$ stat /tmp/test.txt
  File: '/tmp/test.txt'
  Size: 24              Blocks: 8          IO Block: 4096   regular file
Device: fd01h/64769d    Inode: 783925      Links: 2
Access: (0664/-rw-rw-r--)  Uid: ( 5000/   vmail)   Gid: ( 5000/   vmail)
Access: 2016-08-18 20:49:38.419011552 -0400
Modify: 2016-08-18 20:49:07.178995015 -0400
Change: 2016-08-18 20:49:38.191011425 -0400
 Birth: -

$ /usr/lib/dovecot/dovecot-lda -d "test at example.com" -p "/tmp/test.txt"

When I do this, the destination mailbox acts like there's a new message
(I'm using Thunderbird, and the mailbox is highlighted in blue and
bolded, which is the "new mail" behavior in this client).

But when I "check my inbox", i.e., click on the Inbox, I don't see the
new message.

With regard to the filesystem, the message is present and contains the
intended contents. Here's the "stat" output:

$ stat
/var/vmail/example.com/ben/Maildir/cur/1471567777.M685753P32257.example.com,S=24:2,
  File:
'/var/vmail/example.com/ben/Maildir/cur/1471567777.M685753P32257.example.com,S=24:2,'
  Size: 24              Blocks: 8          IO Block: 4096   regular file
Device: fd01h/64769d    Inode: 783925      Links: 2
Access: (0664/-rw-rw-r--)  Uid: ( 5000/   vmail)   Gid: ( 5000/   vmail)
Access: 2016-08-18 20:51:05.647059340 -0400
Modify: 2016-08-18 20:50:58.543055378 -0400
Change: 2016-08-18 20:50:58.543055378 -0400
 Birth: -

Might anyone know why I'm not "seeing" this message in my IMAP client?

Interestingly, I tried another IMAP client (Blue Mail for Android), and
I can actually see the messages there, but they appear in the Inbox as:

(No subject)
<Empty Message>

When I click on the messages, Blue Mail simply displays "No text",
without the quotes.

Surely, I'm overlooking something simple...

Thank you for any help here!

-Ben



Full "doveconf -n" output:

$ doveconf -n
# 2.2.22 (fe789d2): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.13 (7b14904)
# OS: Linux 4.4.0-34-generic x86_64 Ubuntu 16.04.1 LTS
auth_mechanisms = plain login
disable_plaintext_auth = no
listen = *,[::]
log_timestamp = "%Y-%m-%d %H:%M:%S "
mail_max_userip_connections = 100
mail_plugins = " quota"
mail_privileged_group = vmail
passdb {
  args = /etc/dovecot/dovecot-sql.conf
  driver = sql
}
plugin {
  antispam_backend = pipe
  antispam_debug_target = syslog
  antispam_pipe_program = /bin/bash
  antispam_pipe_program_args = /usr/local/bin/sa-learn-pipe.sh
  antispam_pipe_program_notspam_arg = --ham
  antispam_pipe_program_spam_arg = --spam
  antispam_pipe_tmpdir = /tmp
  antispam_spam_pattern_ignorecase = SPAM;JUNK
  antispam_trash_pattern_ignorecase = trash;Deleted *
  antispam_verbose_debug = 1
  quota = dict:user::file:/var/vmail/%d/%n/.quotausage
  quota_rule2 = Trash:storage=+100M
  quota_rule3 = Junk:ignore
  quota_rule4 = INBOX:storage=+100M
  quota_warning = storage=100%% quota-reached 100 %u %d
  quota_warning2 = storage=95%% quota-warning 95 %u %d
  quota_warning3 = storage=80%% quota-warning 80 %u %d
  quota_warning4 = -storage=100%% quota-below below %u %d
  sieve = /var/vmail/%d/%n/.sieve
  sieve_max_redirects = 25
}
postmaster_address = postmaster at example.com
protocols = imap pop3
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener auth-userdb {
    group = vmail
    mode = 0600
    user = vmail
  }
  user = root
}
service imap-login {
  client_limit = 1000
  process_limit = 512
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service quota-below {
  executable = script /usr/local/bin/quota-below.sh
  unix_listener quota-below {
    group = vmail
    mode = 0666
    user = vmail
  }
  user = vmail
}
service quota-reached {
  executable = script /usr/local/bin/quota-reached.sh
  unix_listener quota-reached {
    group = vmail
    mode = 0666
    user = vmail
  }
  user = vmail
}
service quota-warning {
  executable = script /usr/local/bin/quota-warning.sh
  unix_listener quota-warning {
    group = vmail
    mode = 0666
    user = vmail
  }
  user = vmail
}
ssl_cert = </etc/postfix/smtpd.cert
ssl_key = </etc/postfix/smtpd.key
ssl_protocols = !SSLv2 !SSLv3
userdb {
  driver = prefetch
}
userdb {
  args = /etc/dovecot/dovecot-sql.conf
  driver = sql
}
protocol imap {
  mail_plugins = quota imap_quota antispam
}
protocol pop3 {
  mail_plugins = quota
  pop3_uidl_format = %08Xu%08Xv
}
protocol lda {
  mail_plugins = sieve quota
}
protocol lmtp {
  mail_plugins = quota sieve
  postmaster_address = webmaster at localhost
}