To update the DKIM key length to 2048-bit for Office 365 (Microsoft 365), follow these steps:


1. Access the Microsoft 365 Admin Center

2. Go to the Exchange Admin Center

  • In the Admin Center, expand Admin centers in the left-hand menu, and select Exchange.
  • This will open the Exchange Admin Center (EAC).

3. Navigate to DKIM Settings

  • In the EAC, go to protection and then click on dkim under threat management.

4. Select Your Domain

  • You'll see a list of domains associated with your Office 365 account.
  • Select the domain for which you want to update the DKIM key length.

5. Update DKIM key length

  • In the DKIM settings, click on Enable (if DKIM is not already enabled).
  • If DKIM is already enabled, click on Rotate DKIM keys. This process automatically generates new DKIM keys.
  • The default key length for newly generated keys is 2048-bit.

6. Verify DKIM is Working

  • You can verify that DKIM length on www.godmarc.com>Tools>DKIM Record Loopup.

Note: DNS changes can take up to 48 hours to propagate, although they often happen much quicker.


This setup will ensure that your emails are signed with a 2048-bit DKIM key, providing stronger email authentication and security.