Log error : seahub_email_sender.log

Seafile Server
1

hi
since the seafile pro 7.1.12 update. I found this error in seahub_email_sender.log, thank you for your help

[INFO]2021-02-04 16:05:45 PID 25958: Acquiring lock for sending queued emails at /tmp/post_office.lock
[INFO]2021-02-04 16:05:45 PID 25958: Started sending 0 emails with 1 processes.
[INFO]2021-02-04 16:05:45 PID 25958: 0 emails attempted, 0 sent, 0 failed
[INFO]2021-02-04 16:35:45 PID 26704: Acquiring lock for sending queued emails at /tmp/post_office.lock
[INFO]2021-02-04 16:35:45 PID 26704: Started sending 0 emails with 1 processes.
[INFO]2021-02-04 16:35:45 PID 26704: 0 emails attempted, 0 sent, 0 failed
Unknown command: 'send_queued_mail'
Type 'manage.py help' for usage.
Unknown command: 'send_queued_mail'
Type 'manage.py help' for usage.
Unknown command: 'send_queued_mail'
Type 'manage.py help' for usage.
Unknown command: 'send_queued_mail'
Type 'manage.py help' for usage.
Unknown command: 'send_queued_mail'
Type 'manage.py help' for usage.

EDIT: errors are still present with seafile pro 7.1.13