Microsoft 365 - Unblocking Account Blocked by Microsoft

When Microsoft notices an account sending a large volume of spam messages, it will place a block on the account. This block will prohibit the account from sending additional emails until the account has been unblocked, which will result in the user receiving a bounce back message when they attempt to send. This often occurs when an account has been compromised, e.g. the account has been the victim of a phishing attack.

In most cases, accounts that are blocked by Microsoft have also been disabled by DoIT Security. These two processes occur at different times and are controlled by different groups independent of each other. However, in either scenario, the Help Desk still has the ability to remedy the situation.

Important: If the user is sending to a large amount of individual recipients and is getting blocked, please direct them to use one of these services instead: distribution list or Mass Email Service.

Check the status of an account

  1. Log into the Wisc Account Admin site.
  2. Search for the NetID in the top right corner in the search field.
  3. Expand the tab labeled "Office 365."
  4. Click Status.

    Status

  5. Scroll down to "Blocked Address(es)".

    blocked addresses

    Note: This field will list all addresses that have been blocked, including non-primary addresses. If more than one address is listed, you will need to unblock each one individually.

Unblock the Account

Important: Before continuing with these instructions, it is very important that the steps listed in this document: Identifying a compromised NetID in NIDU have been completed. If these steps have already been performed, there is no need to go through them again.

  1. Make sure the steps in Identifying a compromised NetID in NIDU have been completed have been performed. If not, make sure to complete those steps with the customer before proceeding.
  2. Follow the steps listed above to view the status of the account.
  3. Unblock the account by clicking the button labeled Unblock
  4. Refresh the page until it says "Not Blocked" next to "Sending Status" and inform the customer.

    not blocked

Notes:

  • It may take up to 24 hours for a customer to once again be able to send outgoing mail after they've been unblocked following the above process. Please do not escalate these cases to the Office 365 Team, unless the customer is still unable to access/send mail over 24 hours after being unblocked.

Keywords:
wisc account administration site admins administer administering phishing unable sending bounce back status can't cant unable compromised mailbox emails netid service account delivered has failed undeliverable not valid sender spam junk contact delivery messages
Doc ID:
66703
Owned by:
WAA S. in Wisc Account Admin
Created:
2016-09-06
Updated:
2023-02-02
Sites:
DoITHelpDesk-internal, Microsoft365-internal, WiscAccountAdmin-internal