How to block (defederate) a server on Mastodon

Each server on the Fediverse is independent, and can choose to cut off connections to any other server if it wants to do so. This process of blocking other servers on the Fediverse is known as “defederation” or “fediblocking”.

Usually this is done for the sake of user safety, for example if another server is failing to moderate abusive behaviour, but it can be for any reason that the server admin considers important.

If you’re an admin on a Mastodon server, here is how to defederate other servers on the Fediverse:

  1. Log into your admin account on your server’s website
  2. Go to Preferences > Moderation > Federation
  3. Click Add New Domain Block
  4. Enter the domain name of the server you want to block (for example “”)
  5. From the Severity dropdown menu select Suspend
  6. Optionally add comments if you want to remind yourself why you blocked them, or if you have a public list that explains your server’s blocks
  7. Click Create Block

Once you’ve done this, your server will refuse connections from the blocked server and any follows from those servers will be removed.

These blocks work for any Fediverse server type, so you can block non-Mastodon servers as well.

Do I have to do this for every single server I want to block?

By default, blocks are done one at a time. However, you can also import ready-made blocklists which let you block lots of servers at once.

Do I need to defederate subdomains separately too?

No. If you block the main domain, this automatically also defederates all subdomains of that domain.

Is there a less drastic alternative to blocking?

Yes, you can choose Limit from the Severity menu instead of Suspend. Limiting (also known as Silencing) does not cut off connections, and allows follows to carry on, but it hides all posts from that server unless people are following the account that makes them.

What if I change my mind? How do I unblock servers?

To remove a domain block:

  1. Log into your admin account on your server’s website
  2. Go to Preferences > Moderation > Federation
  3. Click on the domain you want to unblock
  4. Click Undo Domain Block

If I unblock a server, will people’s follows be restored?

When an admin defederates a server, that cuts off all the follows between that server and the admin’s server.

Unblocking a server allows people to follow each other again, but it does not automatically restore follows that existed before the defederation happened. This is an important reason to consider carefully before defederating a server.

If you want to distance yourself from a server but don’t want to cut off follows, use the Limit/Silence option instead of Suspend.

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