Block email address office 365

In Office 365, you can block an email address to prevent it from sending emails to your organization. Here are the steps to block an email address in Office 365:

Method 1: Using the Office 365 Admin Center

  1. Sign in to the Office 365 Admin Center with your admin credentials.
  2. Go to Settings > Mail > Mail flow > Rules.
  3. Click on New rule.
  4. Select Block as the rule type.
  5. Enter the email address you want to block in the From field.
  6. Click Save.

Method 2: Using PowerShell

  1. Open PowerShell and connect to your Office 365 tenant using the following command: Connect-ExchangeOnline -UserPrincipalName <your_admin_username> -ShowProgress $true
  2. Run the following command to block an email address: New-TransportRule -Name "Block <email_address>" -From <email_address> -PrependQuotaMessage $false -RejectMessage "This email address is blocked" -RejectMessageEnhanced $true

Replace <email_address> with the email address you want to block.

Method 3: Using the Office 365 Security & Compliance Center

  1. Sign in to the Office 365 Security & Compliance Center with your admin credentials.
  2. Go to Threat management > Policy > Create a new policy.
  3. Select Block as the policy type.
  4. Enter the email address you want to block in the From field.
  5. Click Save.

Note: Blocking an email address will prevent emails from being delivered to your organization, but it will not prevent the sender from sending emails to other recipients outside of your organization.

Also, keep in mind that blocking an email address may not be effective in all cases, as spammers and phishers may use different email addresses or tactics to evade detection. It's always a good idea to combine email blocking with other security measures, such as spam filtering and user education, to protect your organization from email threats.