ZhangHuangbin, here's another log, this time including what I believe is the associated imp log...
Aug 1 16:58:54 mail dovecot: imap-login: Login: user=<myUser@myDomain>, method=PLAIN, rip=clientIP, lip=serverIP, mpid=22577, TLS, TLSv1.2 with cipher cipherID (256/256 bits), session=<mzA8IKIeJfJriWvy>
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Disconnected: Logged out in=36 out=605 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Error: last_login_dict: Failed to write value: dict-server returned failure: sql dict: commit failed: ERROR: duplicate key value violates unique constraint "last_login_pkey"
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Loading modules from directory: /usr/lib/dovecot/modules
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib01_acl_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib02_imap_acl_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib10_last_login_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib10_quota_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib11_imap_quota_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib15_notify_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib20_mail_log_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib20_mailbox_alias_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Module loaded: /usr/lib/dovecot/modules/lib95_imap_sieve_plugin.so
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Added userdb setting: mail=maildir:~/Maildir
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Added userdb setting: plugin/master_user=myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Added userdb setting: plugin/quota_rule=*:bytes=524288000
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Effective uid=2000, gid=2000, home=/var/vmail/vmail1/myDomain/e/v/e/myUser-2024.07.30.18.01.20/
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: Starting transaction
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: Setting 'shared/last-login/imap/myUser@myDomain/myDomain' to '1722531534'
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: conn unix:/run/dovecot/dict: Connecting
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: conn unix:/run/dovecot/dict (pid=614,uid=0): Client connected (fd=8)
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota root: name=user backend=dict args=:proxy::quotadict
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota rule: root=user mailbox=* bytes=524288000 messages=0
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota warning: bytes=524288000 (100%) messages=0 reverse=no command=quota-warning 100 myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota warning: bytes=498073600 (95%) messages=0 reverse=no command=quota-warning 95 myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota warning: bytes=471859200 (90%) messages=0 reverse=no command=quota-warning 90 myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota warning: bytes=445644800 (85%) messages=0 reverse=no command=quota-warning 85 myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Quota grace: root=user bytes=52428800 (10%)
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: quota-dict: user=myUser@myDomain, uri=proxy::quotadict, noenforcing=0
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Namespace : type=private, prefix=, sep=/, inbox=yes, hidden=no, list=yes, subscriptions=yes location=maildir:~/Maildir
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: maildir++: root=/var/vmail/vmail1/myDomain/e/v/e/myUser-2024.07.30.18.01.20//Maildir, index=, indexpvt=, control=, inbox=/var/vmail/vmail1/myDomain/e/v/e/myUser-2024.07.30.18.01.20//Maildir, alt=
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl: initializing backend with data: vfile
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl: acl username = myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl: owner = 1
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl vfile: Global ACLs disabled
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: Namespace : type=shared, prefix=Shared/%u/, sep=/, inbox=no, hidden=no, list=children, subscriptions=yes location=maildir:%Lh/Maildir/:INDEX=%Lh/Maildir/Shared/%Ld/%Ln
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: shared: root=/run/dovecot, index=, indexpvt=, control=, inbox=, alt=
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl: initializing backend with data: vfile
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl: acl username = myUser@myDomain
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl: owner = 0
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: acl vfile: Global ACLs disabled
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: quota: quota_over_flag check: quota_over_script unset - skipping
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: Waiting for dict to finish pending operations
Aug 1 16:58:54 mail dovecot: imap: Error: DETAIL: Key (username, domain)=(myUser@myDomain, myDomain) already exists. (reply took 0.058 secs (0.014 in dict wait, 0.034 in other ioloops, 0.000 in locks, async-id reply 0.038 secs ago, started on dict-server 0.041 secs ago, took 0.041 secs))
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: Dict transaction finished
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: conn unix:/run/dovecot/dict (pid=614,uid=0): Disconnected: Connection closed (fd=8)
Aug 1 16:58:54 mail dovecot: imap(myUser@myDomain)<22577><mzA8IKIeJfJriWvy>: Debug: dict(proxy)<myUser@myDomain>: Waiting for dict to finish pending operations