Dovecot not serving all messages through IMAP

Question

I have a Debian / Dovecot / Postfix standard setup. Additionally I am running notmuchmail indexer to quickly search for messages. As a mail client I use emClient on Windows, I also got Rainloop Webmail running.

I used notmuchmail to search for a particular message and i found it, received around 5 years ago. When I check with emClient, the messages dated back only until 3 1/2 years ago. First I suspected emClient to not have downloaded all messages, but then, checking with Rainloop, I also saw the oldest message visible via IMAP is 3 1/2 years old.

Searching the problem, it is suggested to resyncronize the mail client by deleting the dovecot-uidlist in my Maildir (https://www.dovecot.org/list/dovecot/2013-October/092803.html), which i did. emClient resynced all messages accordingly BUT nothing changed, the oldest message is 3 1/2 years old.

So now i am at a loss... Is there anything else i can do to have access to ALL my messages through IMAP. My Server is running Dovecot 2.2.13.

output "of dovecot -n"

# 2.2.13: /etc/dovecot/dovecot.conf
# OS: Linux 3.16.0-4-amd64 x86_64 Debian 8.9
login_trusted_networks = 192.168.1.0/24
mail_location = maildir:~/Maildir
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 ihave
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
  separator = /
}
passdb {
  driver = pam
}
plugin {
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
}
protocols = " imap sieve"
quota_full_tempfail = yes
service auth {
  unix_listener auth-userdb {
    mode = 0600
    user = username
  }
}
service managesieve-login {
  inet_listener sieve {
    port = 4190
  }
}
ssl = required
ssl_cert = </etc/letsencrypt/live/a.b.com/fullchain.pem
ssl_cipher_list = AES128+EECDH:AES128+EDH
ssl_dh_parameters_length = 2048
ssl_key = </etc/letsencrypt/live/a.b.com/privkey.pem
ssl_protocols = !SSLv2 !SSLv3
userdb {
  driver = passwd
}
protocol lda {
  info_log_path =
  log_path =
  mail_plugins = " sieve"
}

Answer 1

Broken Indexes and Other Mailbox Issues

This sounds like an issue with a broken mailbox index, which is something Dovecot's usually very good at fixing on its own. In case it fails, you can force Dovecot to repair indexes and other issues using

doveadm force-resync -u <username> <mailbox>

in case of the user johndoe and mails not showing up in his inbox, the command would be

doveadm force-resync -u johndoe INBOX

Running doveadm -Dv force-resync ... (debug and verbose output) might provide more insight on any issues.

Client Side Issues

In rare cases, mail clients might suffer under inconsistent local data, especially when mails have been renumbered on the server side due to mailbox issues. Some mail clients know "repair" functions, other might require you to remove and recreate the mailbox and thus trigger a full sync.