I just got an event invitation and clicked accept then got this error: "An error occurred while send

I just got an event invitation and clicked accept then got this error:

"An error occurred while sending mail. The mail server responded: 554 5.2.0 STOREDRV.Submission.Exception:OutboundSpamException; Failed to process message due to a permanent exception with message WASCL UserAction verdict is not None. Actual verdict is HipNotify, ShowTierUpgrade. OutboundSpamException: WASCL UserAction verdict is not None. Actual verdict is HipNotify, ShowTierUpgrade. [Hostname=LNXP265MB0394.GBRP265.PROD.OUTLOOK.COM]. Please check the message and try again."