Odd replication behaviour

[James Pattinson]

Hi,

I have just built a new pair of similar machines both running CentOS 8.2 (selinux disabled) and Dovecot 2.3.8 (9df20d2db).

One machine is a VPS (host A) and one is on my home network (host B). The idea is that they are set up in a master/master config with Dovecot replication.

I seem to have this 95% working but there is one strange issue I can’t work out.

Currently B is a perfect replica of A. I have pointed an instance of Thunderbird at it, and I can see all my mails. If I delete any mails or change any flags, I see the same changes almost instantly on the A side.

PROBLEM: if host A receives a new mail, I don’t see it on B until I do ‘something’ to change metadata, for example deleting any random email, or marking an email as read on EITHER side causes the new email to appear almost instantly on the B side.

I would have expected emails on B to appear immediately. Am I doing something wrong?

Extra info -  my mailboxes are in Maildir format with single OS user (vmail). I have about 4000 emails in the Inbox and about 30k in other folders.

There are only 5 users and I’m using passdb as the very simple backend.

Replication is via doveadm on a specified port (not SSH). Some output from dovecot -n is below.

Cheers
James

HOST A

# 2.3.8 (9df20d2db): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.8 (b7b03ba2)
# OS: Linux 4.18.0-193.28.1.el8_2.x86_64 x86_64 CentOS Linux release 8.2.2004 (Core)  xfs
# Hostname: hosta.domain
auth_mechanisms = plain login
doveadm_password = # hidden, use -P to show it
doveadm_port = 4040
first_valid_uid = 1000
mail_debug = yes
mail_home = /srv/vmail/%u
mail_location = maildir:/srv/vmail/%u
mail_plugins = notify replication
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
mbox_write_locks = fcntl
namespace inbox {
  inbox = yes
  location = 
  mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
  }
  mailbox Junk {
    auto = subscribe
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    auto = subscribe
    special_use = \Trash
  }
  prefix = 
}
passdb {
  args = scheme=BLF-CRYPT username_format=%u /etc/dovecot/users
  driver = passwd-file
}
plugin {
  mail_replica = tcp:b.b.b.b:4040
  sieve = file:~/sieve;active=~/.dovecot.sieve
  sieve_before = /var/mail/SpamToJunk.sieve
}
protocols = imap lmtp
service aggregator {
  fifo_listener replication-notify-fifo {
    group = root
    mode = 0660
    user = vmail
  }
  unix_listener replication-notify {
    group = root
    mode = 0660
    user = vmail
  }
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service doveadm {
  inet_listener {
    port = 4040
  }
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service replicator {
  process_min_avail = 1
  unix_listener replicator-doveadm {
    mode = 0600
    user = vmail
  }
}
ssl = required
ssl_cert = </etc/letsencrypt/live/mail2.pattinson.org/fullchain.pem
ssl_cipher_list = PROFILE=SYSTEM
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_min_protocol = TLSv1.2
ssl_prefer_server_ciphers = yes
userdb {
  args = username_format=%u /etc/dovecot/users
  default_fields = uid=vmail gid=mail home=/srv/vmail/%u
  driver = passwd-file
}
protocol lmtp {
  mail_plugins = sieve
}
protocol lda {
  mail_plugins = notify replication sieve
}

HOST B

# 2.3.8 (9df20d2db): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.8 (b7b03ba2)
# OS: Linux 4.18.0-193.28.1.el8_2.x86_64 x86_64 CentOS Linux release 8.2.2004 (Core)  ext4
# Hostname: hostb
auth_mechanisms = plain login
doveadm_password = # hidden, use -P to show it
doveadm_port = 4040
first_valid_uid = 1000
mail_debug = yes
mail_home = /srv/vmail/%u
mail_location = maildir:/srv/vmail/%u
mail_plugins = notify replication
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
mbox_write_locks = fcntl
namespace inbox {
  inbox = yes
  location = 
  mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
  }
  mailbox Junk {
    auto = subscribe
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    auto = subscribe
    special_use = \Trash
  }
  prefix = 
}
passdb {
  args = scheme=BLF-CRYPT username_format=%u /etc/dovecot/users
  driver = passwd-file
}
plugin {
  mail_replica = tcp:a.a.a.a:4040
  sieve = file:~/sieve;active=~/.dovecot.sieve
  sieve_before = /var/mail/SpamToJunk.sieve
}
protocols = imap lmtp
service aggregator {
  fifo_listener replication-notify-fifo {
    group = root
    mode = 0660
    user = vmail
  }
  unix_listener replication-notify {
    group = root
    mode = 0660
    user = vmail
  }
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service doveadm {
  inet_listener {
    port = 4040
  }
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service replicator {
  process_min_avail = 1
  unix_listener replicator-doveadm {
    mode = 0600
    user = vmail
  }
}
ssl = required
ssl_cert = </etc/letsencrypt/live/mail2.pattinson.org/fullchain.pem
ssl_cipher_list = PROFILE=SYSTEM
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_min_protocol = TLSv1.2
ssl_prefer_server_ciphers = yes
userdb {
  args = username_format=%u /etc/dovecot/users
  default_fields = uid=vmail gid=mail home=/srv/vmail/%u
  driver = passwd-file
}
protocol lmtp {
  mail_plugins = sieve
}
protocol lda {
  mail_plugins = notify replication sieve
}