Mail can not be sent - Grund 550-mailbox unavailable 550 Insufficient security or privacy level.

Mail can not be sent - Grund 550-mailbox unavailable 550 Insufficient security or privacy level.

Hello,

I just realised that I'm not able to send mails using Zoho

Massage:
Die Nachricht konnte nicht versendet werden;Grund:550-Requested action not taken: mailbox unavailable550 Insufficient security or privacy level.

Do I have to change any settings ?

best regards

Bernd