Dovecot error:- delivery temporarily suspended: connect to private/dovecot-lmtp]: Connection refused

Hi All,
I am new on CentOS 7. I have installed Postfix & working properly. But in dovecot when trying to send mail from outlook 2016 in error login dovecot showing error:-
delivery temporarily suspended: connect to private/dovecot-lmtp]: Connection refused
dovecot -n
dovecot -n
# 2.2.36 (1f10bfa63): /etc/dovecot/dovecot.conf
# OS: Linux 3.10.0-1160.88.1.el7.x86_64 x86_64 CentOS Linux release 7.9.2009 (Core) xfs
# Hostname: Hostname
auth_mechanisms = plain login
auth_verbose = yes
debug_log_path = /var/log/dovecot-debug.log
dict {
quotadict = mysql:/etc/dovecot/dovecot-dict-quota.conf
}
disable_plaintext_auth = no
first_valid_gid = 12
first_valid_uid = 998
info_log_path = /var/log/dovecot-info.log
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
listen = *
lmtp_save_to_detail_mailbox = yes
log_path = /var/log/dovecot.log
mail_debug = yes
mail_location = maildir:/var/mail/vmail/%d/%n
passdb {
args = /etc/dovecot/dovecot.deny
deny = yes
driver = passwd-file
name = passwd-file
}
passdb {
args = /etc/dovecot/dovecot-mysql.conf
driver = sql
}
service auth {
unix_listener /var/spool/postfix/private/auth {
group = postfix
mode = 0666
user = postfix
}
unix_listener auth-userdb {
group = mail
mode = 0666
user = vmail
}
}
service dict {
unix_listener dict {
group = mail
mode = 0666
user = vmail
}
}
service imap-login {
inet_listener imap {
port = 143
}
}
service imap {
vsz_limit = 256 M
}
service managesieve-login {
inet_listener sieve {
port = 4190
}
process_min_avail = 0
service_count = 1
vsz_limit = 64 M
}
service pop3-login {
inet_listener pop3 {
port = 110
}
}
ssl_ca = </etc/letsencrypt/live/Hostname.in/fullchain.pem
ssl_cert = </etc/letsencrypt/live/Hostname.in/cert.pem
ssl_key = # hidden, use -P to show it
userdb {
driver = sql
}
userdb {
args = /etc/dovecot/dovecot-mysql.conf
driver = sql
}
protocol lda {
mail_plugins = quota sieve
postmaster_address = [email protected]
}
protocol imap {
imap_client_workarounds = delay-newmail
mail_plugins = quota imap_quota trash
}
protocol lmtp {
mail_plugins = quota sieve
}
protocol pop3 {
mail_plugins = quota
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
pop3_uidl_format = %08Xu%08Xv
}

Mail log:-

May 9 15:54:21 dedi postfix/error[21864]: 693CE1ABDA9: to=<[email protected]>, relay=none, delay=256639, delays=256639/0.05/0/0.01, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to hostname[private/dovecot-lmtp]: Connection refused)
May 9 15:54:21 dedi postfix/lmtp[21857]: 197501A839F: to=<root@hostname>, orig_to=<root>, relay=none, delay=1501, delays=1501/0.05/0.01/0, dsn=4.4.1, status=deferred (connect to hostname[private/dovecot-lmtp]: Connection refused)
May 9 15:54:21 dedi postfix/lmtp[21861]: 820EF1A83AC: to=<root@hostname>, orig_to=<root>, relay=none, delay=560, delays=560/0.05/0.01/0, dsn=4.4.1, status=deferred (connect to hostname[private/dovecot-lmtp]: Connection refused)
May 9 15:54:21 dedi postfix/error[21864]: 39D171ABDB1: to=<[email protected]>, relay=none, delay=105429, delays=105429/0.06/0/0, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to hostname[private/dovecot-lmtp]: Connection refused)
May 9 15:54:21 dedi postfix/lmtp[21859]: 0623C1A83AD: to=<root@hostname>, orig_to=<root>, relay=none, delay=510, delays=510/0.06/0/0, dsn=4.4.1, status=deferred (connect to hostname[private/dovecot-lmtp]: Connection refused)