==== Required information ====
- iRedMail version (check /etc/iredmail-release):
- Linux/BSD distribution name and version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.8 MARIADB edition.
- Linux/BSD distribution name and version: CentOS Linux release 7.4.1708 (Core)
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hi,

Recently we repeated getting alot of the below warning message in dovecot/imap.log for some of users, but they can normally send and receive email.
Could anyone know what happening?

Apr 16 16:18:22 mail-srv dovecot: imap(aaa@aaa.com): Warning: Maildir /var/vmail/vmail1/aaa.com/a/a/a/aaa-2017.12.13.16.19.06//Maildir: Synchronization took 613 seconds (0 new msgs, 0 flag change attempts, 0 expunge attempts)

Apr 16 16:18:24 mail-srv dovecot: imap(aaa@aaa.com): Warning: Maildir: Scanning /var/vmail/vmail1/aaa.com/a/a/a/aaa-2017.12.13.16.19.06//Maildir/cur took 497 seconds (66428 readdir()s, 0 rename()s to cur/, why=0x1)

[root@mail-srv dovecot]# doveconf -n
# 2.2.32 (dfbe293d4): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.20 (7cd71ba)
# OS: Linux 3.10.0-693.21.1.el7.x86_64 x86_64 CentOS Linux release 7.4.1708 (Core)
auth_master_user_separator = *
auth_mechanisms = PLAIN LOGIN
deliver_log_format = from=%{from}, envelope_sender=%{from_envelope}, subject=%{subject}, msgid=%m, size=%{size}, %$
dict {
  acl = mysql:/etc/dovecot/dovecot-share-folder.conf
  quotadict = mysql:/etc/dovecot/dovecot-used-quota.conf
}
first_valid_uid = 2000
last_valid_uid = 2000
listen = * [::]
mail_gid = 2000
mail_location = maildir:%Lh/Maildir/:INDEX=/var/vmail-indexes/%Ld/%Ln/
mail_plugins = quota mailbox_alias acl mail_log notify stats
mail_uid = 2000
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
namespace {
  inbox = yes
  location =
  mailbox Archive {
    auto = no
    special_use = \Archive
  }
  mailbox Archives {
    auto = no
    special_use = \Archive
  }
  mailbox "Deleted Messages" {
    auto = no
    special_use = \Trash
  }
  mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
  }
  mailbox Junk {
    auto = subscribe
    special_use = \Junk
  }
  mailbox "Junk E-mail" {
    auto = no
    special_use = \Junk
  }
  mailbox Sent {
    auto = subscribe
    special_use = \Sent
  }
  mailbox "Sent Items" {
    auto = no
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    auto = no
    special_use = \Sent
  }
  mailbox Spam {
    auto = no
    special_use = \Junk
  }
  mailbox Trash {
    auto = subscribe
    special_use = \Trash
  }
  prefix =
  separator = /
  type = private
}
namespace {
  list = children
  location = maildir:%%Lh/Maildir/:INDEX=/var/vmail-indexes/%Ld/%Ln/Shared/%%Ld/%%Ln:INDEXPVT=/var/vmail-indexes/%Ld/%Ln/Shared/%%Ld/%%Ln
  prefix = Shared/%%u/
  separator = /
  subscriptions = yes
  type = shared
}
passdb {
  args = /etc/dovecot/dovecot-mysql.conf
  driver = sql
}
passdb {
  args = /etc/dovecot/dovecot-master-users
  driver = passwd-file
  master = yes
}
plugin {
  acl = vfile
  acl_shared_dict = proxy::acl
  mail_log_events = delete undelete expunge mailbox_delete mailbox_rename
  mail_log_fields = uid box msgid size from subject
  mailbox_alias_new = Sent Messages
  mailbox_alias_new2 = Sent Items
  mailbox_alias_old = Sent
  mailbox_alias_old2 = Sent
  quota = dict:user::proxy::quotadict
  quota_grace = 10%%
  quota_warning = storage=100%% quota-warning 100 %u
  quota_warning2 = storage=95%% quota-warning 95 %u
  quota_warning3 = storage=90%% quota-warning 90 %u
  quota_warning4 = storage=85%% quota-warning 85 %u
  sieve = %Lh/sieve/dovecot.sieve
  sieve_before = /var/vmail/sieve/dovecot.sieve
  sieve_dir = %Lh/sieve
  sieve_global_dir = /var/vmail/sieve
  sieve_max_redirects = 30
  stats_refresh = 30 secs
  stats_track_cmds = yes
}
protocols = pop3 imap sieve lmtp
service auth {
  unix_listener /var/spool/postfix/private/dovecot-auth {
    group = postfix
    mode = 0666
    user = postfix
  }
  unix_listener auth-master {
    group = vmail
    mode = 0666
    user = vmail
  }
  unix_listener auth-userdb {
    group = vmail
    mode = 0660
    user = vmail
  }
}
service dict {
  unix_listener dict {
    group = vmail
    mode = 0660
    user = vmail
  }
}
service imap-login {
  process_limit = 500
  service_count = 1
}
service lmtp {
  executable = lmtp -L
  inet_listener lmtp {
    address = 127.0.0.1
    port = 24
  }
  process_min_avail = 5
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
  user = vmail
}
service managesieve-login {
  inet_listener sieve {
    address = 127.0.0.1
    port = 4190
  }
}
service pop3-login {
  service_count = 1
}
service quota-warning {
  executable = script /usr/local/bin/dovecot-quota-warning.sh
  unix_listener quota-warning {
    group = vmail
    mode = 0660
    user = vmail
  }
}
service stats {
  fifo_listener stats-mail {
    mode = 0644
    user = vmail
  }
  inet_listener {
    address = 127.0.0.1
    port = 24242
  }
}
ssl = required
ssl_ca = </etc/letsencrypt/live/imap.innovax.hk/fullchain.pem
ssl_cert = </etc/letsencrypt/live/imap.innovax.hk/cert.pem
ssl_cipher_list = ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5
ssl_dh_parameters_length = 2048
ssl_key =  # hidden, use -P to show it
ssl_prefer_server_ciphers = yes
ssl_protocols = !SSLv2 !SSLv3
syslog_facility = local5
userdb {
  args = /etc/dovecot/dovecot-mysql.conf
  driver = sql
}
protocol lda {
  lda_mailbox_autocreate = yes
  lda_mailbox_autosubscribe = yes
  mail_plugins = quota mailbox_alias acl mail_log notify stats sieve
  postmaster_address = root
}
protocol lmtp {
  lmtp_save_to_detail_mailbox = yes
  mail_plugins = quota sieve
  postmaster_address = postmaster
  recipient_delimiter = +
}
protocol imap {
  imap_client_workarounds = tb-extra-mailbox-sep
  mail_max_userip_connections = 30
  mail_plugins = quota mailbox_alias acl mail_log notify stats imap_quota imap_acl imap_stats
}
protocol pop3 {
  mail_max_userip_connections = 30
  mail_plugins = quota mailbox_alias acl mail_log notify stats
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
  pop3_uidl_format = %08Xu%08Xv
}

Many thanks.