duplicated mail in users inbox only

[Tom Priebe]

Hello,

one of my users has the issue that some mails seem to get doubled --
but only in their inbox. The mail is bcc'd to them and the original
recipient receives one copy as intended. The log shows nothing
extraordinary, postfix, dovecot and sieve are certain that they
received and delivered one single mail (per user).

Further research showed that the doubled mails' mailbox files have the
same inode, which seems inexplicable.

I'm using dovecot 2.2.13 replicated over two servers (Master-Master).
Duplication seems to happen regardless of the receiving server, yet
still not all mails they receive with them in bcc are duplicated.

Here's doveconf -n

> # 2.2.13: /etc/dovecot/dovecot.conf
> # OS: Linux 3.16.0-4-amd64 x86_64 Debian 8.3 
> auth_gssapi_hostname = mail.net.t-labs.tu-berlin.de
> auth_mechanisms = login plain gssapi
> auth_username_format = %n
> auth_verbose = yes
> default_client_limit = 1024
> default_process_limit = 1024
> default_vsz_limit = 512 M
> doveadm_password = supersecretpassword
> listen = *, [::]
> log_timestamp = "%Y-%m-%d %H:%M:%S "
> login_log_format_elements = user=<%u> method=%m rip=%r lip=%l
> %c %
> mail_location = maildir:~/Maildir
> mail_plugins = " notify replication"
> mail_privileged_group = mail
> 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 = 
> }
> passdb {
>   args = failure_show_msg=yes dovecot
>   driver = pam
> }
> plugin {
>   mail_replica = remote:vmail at mail1.inet.tu-berlin.de
>   sieve = /mail/home/%u/.dovecot.sieve
>   sieve_dir = /mail/home/%u/sieve
>   sieve_max_redirects = 20
> }
> postmaster_address = postmaster at net.t-labs.tu-berlin.de
> protocols = imap sieve
> service aggregator {
>   fifo_listener replication-notify-fifo {
>     user = vmail
>   }
>   unix_listener replication-notify {
>     user = vmail
>   }
> }
> service anvil {
>   chroot = empty
>   client_limit = 4096
>   process_limit = 1
> }
> service auth {
>   client_limit = 4096
>   unix_listener /var/spool/postfix/private/auth {
>     group = postfix
>     mode = 0660
>     user = postfix
>   }
>   unix_listener auth-master {
>     mode = 0600
>     user = vmail
>   }
>   unix_listener auth-userdb {
>     mode = 0600
>     user = vmail
>   }
>   user = root
> }
> service doveadm {
>   inet_listener {
>     port = 12345
>     ssl = yes
>   }
> }
> service imap-login {
>   client_limit = 1024
>   inet_listener imap {
>     port = 143
>   }
>   inet_listener imaps {
>     port = 993
>     ssl = yes
>   }
>   process_limit = 100
>   process_min_avail = 2
>   service_count = 50
> }
> service imap {
>   process_limit = 1024
> }
> service managesieve-login {
>   client_limit = 1024
>   executable = /usr/lib/dovecot/managesieve-login
>   inet_listener sieve {
>     port = 4190
>   }
>   process_limit = 1024
>   process_min_avail = 20
>   service_count = 1
> }
> service managesieve {
>   process_limit = 1024
> }
> service pop3-login {
>   client_limit = 1024
>   inet_listener pop3 {
>     port = 110
>   }
>   inet_listener pop3s {
>     port = 995
>     ssl = yes
>   }
>   process_limit = 100
>   process_min_avail = 2
>   service_count = 50
> }
> service pop3 {
>   process_limit = 1024
> }
> service replicator {
>   process_min_avail = 1
>   unix_listener replicator-doveadm {
>     group = vmail
>     mode = 0660
>   }
> }
> ssl = required
> ssl_ca = </etc/ssl/certs/TUB-CA.pem
> ssl_cert = </etc/ssl/certs/mail.inet.tu-berlin.de.crt
> ssl_cipher_list =
> EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+S
> HA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aR
> SA:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4
> ssl_client_ca_dir = /etc/ssl/certs
> ssl_key = </etc/ssl/private/mail.inet.tu-berlin.de.pem
> ssl_prefer_server_ciphers = yes
> ssl_protocols = !SSLv2 !SSLv3
> userdb {
>   driver = passwd
>   override_fields = home=/mail/home/%u uid=vmail gid=vmail
> allow_all_users=yes
> }
> protocol lda {
>   auth_socket_path = /var/run/dovecot/auth-master
>   mail_plugins = " notify replication sieve"
> }
> protocol sieve {
>   managesieve_logout_format = bytes=%i/%o
>   managesieve_max_line_length = 65536
>   managesieve_notify_capability = mailto
>   managesieve_sieve_capability = fileinto reject envelope encoded-
> character vacation subaddress comparator-i;ascii-num eric relational
> regex imap4flags copy include variables body enotify environment
> mailbox date ihave
> }

Has anyone any suggestions what went wrong? Is this a dovecot
configuration issue or is something broken?

Regards,
Tom

-- 

Group "Intelligent Networks" (INET)
Technische Universität Berlin
Marchstr. 23 MAR4-4
D-10587 Berlin
TEL: +49-30-314-78537
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