关于 dovecot 的日志配置，请检查 conf.d/10-logging.conf 文件，
特别需要提示的是将 错误/信息 文件分开保存，建议分别设置 log_path / info_log_path 参数路径
# Log file to use for error messages. "syslog" logs to syslog,
# /dev/stderr logs to stderr.
#log_path = syslog
# 错误日志路径
log_path=/var/log/dovecot/dovecot-error.log # Log file to use for informational messages. Defaults to log_path.
# 信息日志路径
info_log_path =/var/log/dovecot/dovecot-info.log # Log file to use for debug messages. Defaults to info_log_path.
# 调试日志路径
debug_log_path = /var/log/dovecot/dovecot-debug.log