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What should I do if my Office 365 account is blocked? | BT Business

What should I do if my Office 365 account is blocked?

If you get an error message when using email software (such as Outlook) or when you sign in to Microsoft Office 365, your account may have been blocked. This is done to protect your account reputation and other internet users.

An account is blocked when it is believed:

  • to have been compromised and is being used fraudulently without your knowledge, or
  • a bulk mail you have sent, has used a distribution list that contains multiple invalid email addresses.

An account can be compromised when someone using a computer clicks on a link in a phishing email or if someone visits a disreputable website.

A compromised account can be used to send spam email which exceeds the service limits. If the service limits are exceeded then the account will be automatically blocked.

Before an account can be unblocked you must perform all the following steps:


Step 1: Make sure that your computer isn't compromised

A) Make sure that you have Windows Update turned on (Windows users only).

B) If antivirus software isn't installed on your computer, we recommend that you install antivirus software and then run a scan to make sure that no malicious software is installed on the computer. You can download free anti-malware or antivirus software from the Microsoft website.


Step 2: Make sure that the attacker can't log on to your Office 365 account

A) Change your password immediately.

B) Don't reuse any recent passwords or use anything it's easy to guess.

C) Change your security question and answer immediately.


Step 3: Additional precautionary steps

A) Make sure that you verify your sent items. You may have to inform people on your contacts list that your account was compromised. The attacker may have asked them for money, spoofing, for example, that you were stranded in a different country and needed money, or the attacker may send them a virus to also hijack their computers.

B) Any other service that used this Exchange account as its alternative email account may have been compromised. First, perform these steps for your Office 365 subscription, and then perform these steps for your other accounts.


Completed all the above?

Once you've completed all these steps, please call our support team on 0800 800 154 to unblock your account.

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