'550 5.7.705 Service unavailable. Access denied, tenant has exceeded threshold

Question

Hello

My domain outgoing emails have been blocked by Microsoft365.

whenever we try sending out an email to other domains, we receive an error message " '550 5.7.705 Service unavailable. Access denied, tenant has exceeded threshold. "

Contacting the support agent does not help because he communicated by email and we cannot reply him back.

we have disabled the outlook connectors and also the compromised user's password has been changed.

Any ideas what more can we do to resolve the issue.

Answer 1

Did you mean that you are using Exchange Server and cannot send message to all M365 organizations?

 

According to the error message : '550 5.7.705 Service unavailable. Access denied, tenant has exceeded threshold. " I think you may have read this documents: Fix NDR error 5.7.700 through 5.7.750 in Exchange Online - Exchange | Microsoft Learn

Common causes are compromised on-premises servers or compromised admin accounts that have been used to create connectors. Either condition can allow spam to pass through your organization.

To remove this block, you need to remove the connectors as you have done “we have disabled the outlook connectors and also the compromised user's password has been changed”.

 

Lastly you will need to contact Microsoft Support to unblock the tenant. Contact O365 Support to unblock your tenant which is blocked from sending email.