SMTP not able to send mail

[KimCK]

Anyone has a hint?

have an office user who is also set as the shop contact email. 

I use smtp.office365.com, port 587 and TLS (or SSL) and the user and password. Then i get Expected response code 250 but got code "", with message "" back. 

If i use none, in encryption then i get this response back "Expected response code 250 but got code "451", with message "451 5.7.3 STARTTLS is required to send mail [MM0P280CA0037.SWEP280.PROD.OUTLOOK.COM 2023-08-11T14:46:55.792Z"''

I can with ease send mails using this account from PowerShell on my laptop using the same settings.

Thanks