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Hi,
We have been sending automated emails through a python script for a while now and suddenly getting this error:
Failed to send an E-mail through the specified SMTP server [smtp.office365.com]:
Mailbox unavailable. The server response was: 5.2.252 Sender throttled due to continuous send as denied errors.
[Hostname=BN9PR12MB5179.namprd12.prod.outlook.com]
All of the login/password information is correct in the python script for sending the email, so why is this suddenly happening?
Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.
It is scan to email. Maybe 5 send an hour.
Also, the issue is on and off which wouldn't make sense if it was https://docs.microsoft.com/en-us/exchange/troubleshoot/send-emails/smtp-submission-improvements#new-throttling-limit-for-concurrent-connections-that-submitmessages
It is working currently.
Good call but yet to hear from MS to clarify this part.
in our part the message we got was that exactly that too many errors had occurred so we were throttled. our developers had a few outdated email contacts in their reporting subscriptions so we told them to quit using that as a way of checking for contacts instead use a distribution list which get updated as soon as a person leaves the company or has a name change and their alias changes e,t,c they get removed from the distribution list preventing their reports to keep sending emails to disabled users which will cause bounce back emails which caused the sending account to get throttled in our case.