Send mails through scheduler event but last some mails get error

I send mail in Welcome message on customer doctype mail-id using api and scheduler event through and i have many customer data which in message send successfully i check manually it is perfect and scheduler use that scheduler through some customer to mail send successfully but last some mail get error.

I will check in Email Queue in Generate Error like:
File “/home/frappe/frappe-bench/apps/frappe/frappe/email/doctype/email_queue/”, line 143, in send
File “/usr/lib/python3.10/”, line 902, in sendmail
(code, resp) =
File “/usr/lib/python3.10/”, line 571, in data
raise SMTPDataError(code, repl)

I think, it’s an email issue, so again reset the email password and try it.

Hello @NCP I checked it’s not email issue it checked using manually send it is successfully send but when i scheduler set and scheduler send one by one automatic send in system that time this error generate.