The mail could not be sent to the recipients because of the mail server failure. (Sending Mail using Account 2 (2021-02-01T13:38:08). Exception Message: Cannot send mails to mail server. (The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM [SG2PR06CA0228.apcprd06.prod.outlook.com]). )
I had no issues when I tried using my Gsuite Email.