Mastodon Relay vs Direct Follow: Bandwidth and Quality Tradeoff

When you run a Mastodon server, you decide how posts from other instances reach your users. You can either subscribe to a relay or ask users to follow accounts directly. Each method affects your server bandwidth and the quality of content your users see. This article explains the technical differences between relays and direct follows. It covers bandwidth usage, content relevance, and moderation control so you can choose the right approach for your instance.

How Relays and Direct Follows Work in Mastodon

Mastodon uses the ActivityPub protocol to exchange posts between instances. When User A on Instance X follows User B on Instance Y, Instance X sends a Follow activity. Instance Y then pushes new posts from User B to Instance X. This is a direct follow. It creates a one-to-one link between the two accounts.

A relay works differently. A relay is a special Mastodon account that acts as a hub. When Instance X subscribes to a relay, the relay sends all public posts from every instance connected to that relay to Instance X. The relay does not filter by user. Instance X receives every post from every participating instance, regardless of whether any user on Instance X follows those accounts.

Bandwidth Consumption

Direct follows consume bandwidth proportional to the number of followed accounts and their posting frequency. If your users follow 100 accounts that each post 10 times per day, your server receives roughly 1,000 posts per day. You can estimate bandwidth as the sum of post sizes from all followed accounts.

Relays consume bandwidth proportional to the total posting volume of all instances connected to the relay. If the relay connects to 1,000 instances and each instance produces 500 posts per day, your server receives 500,000 posts per day. This can be 100 to 1,000 times more bandwidth than direct follows alone. Small instances with limited server resources often find relay bandwidth unsustainable.

Content Relevance and Quality

Direct follows give users control over content relevance. Users see only posts from accounts they chose to follow. The federated timeline remains empty or shows only posts from followed accounts if the server admin configures it that way. Users rarely see spam or off-topic content because they curate their follows.

Relays fill the federated timeline with every public post from connected instances. This includes posts in languages your users may not understand, spam, and content they find irrelevant. The quality of the federated timeline depends entirely on the moderation policies of the instances connected to the relay. If one poorly moderated instance joins the relay, your server receives its spam until you remove the relay subscription.

Moderation Overhead

With direct follows, moderation is minimal. Your moderators handle reports from your users about specific accounts. The workload scales with the number of active users and their follows, not with the size of the fediverse.

With relays, moderation overhead increases significantly. Your server ingests posts from many instances you did not choose. You must monitor the federated timeline for rule violations. You may need to silence or suspend entire instances that produce problematic content. This can turn into a full-time task for larger relays.

Steps to Configure Relays and Direct Follows

The following steps show how to add a relay subscription and how to verify direct follow behavior. You need admin access to your Mastodon server.

Add a Relay Subscription

1. Sign in as admin
   Log into your Mastodon instance with an account that has the Admin or Moderator role.
2. Open Administration settings
   Click the gear icon in the top-right corner, then select Administration from the dropdown menu.
3. Navigate to Relays
   In the left sidebar, click Relays. This page lists all relay subscriptions for your instance.
4. Add a new relay
   Click the Add new relay button. Paste the relay inbox URL provided by the relay operator. A typical relay URL looks like https://relay.example.com/inbox.
5. Confirm the subscription
   Click Submit. Mastodon sends a Follow activity to the relay. The relay must accept the subscription for posts to start flowing. Check the relay status column; it should show Enabled.
6. Monitor bandwidth usage
   After 24 hours, check your server bandwidth logs or use the Mastodon admin dashboard to see incoming traffic. If bandwidth exceeds your limit, disable or remove the relay.

Verify Direct Follow Behavior

1. Create a test account on a different instance
   On a separate Mastodon instance, create a new account that will post public content.
2. Follow the test account from your instance
   On your instance, search for the test account and click Follow. Your server sends a Follow activity to the remote instance.
3. Post from the test account
   Log into the test account and publish a public post. The remote instance pushes the post to your server via ActivityPub.
4. Check the federated timeline
   On your instance, open the federated timeline. With no relay active, the timeline shows only posts from accounts your users follow. The test post appears because you followed the test account.
5. Remove the follow
   Unfollow the test account. New posts from that account stop appearing on your server. This confirms that direct follows control content flow precisely.

Common Misconceptions and Edge Cases

Relays Replace Direct Follows

Some admins believe that using a relay makes direct follows unnecessary. This is false. Relays and direct follows operate independently. Even with a relay active, your users must follow accounts to see their posts in the Home timeline. The relay only fills the federated timeline. Users still need direct follows for personalized feeds.

Relays Guarantee Content Quality

Joining a relay does not guarantee high-quality content. The relay operator may accept any instance. If the relay has no moderation policy, your server receives posts from instances that host spam, hate speech, or illegal material. Always research the relay operator’s moderation rules before subscribing.

Direct Follows Protect Bandwidth Completely

Direct follows reduce bandwidth but do not eliminate it. If your users follow thousands of accounts on high-volume instances, bandwidth can still grow. Each follow creates a persistent connection that pushes posts. For very large instances with tens of thousands of follows, bandwidth may approach relay levels. Monitor your server metrics regardless of the method you choose.

Mastodon Relay vs Direct Follow: Feature Comparison

Item	Relay Subscription	Direct Follow
Bandwidth usage	High, proportional to total instance count on the relay	Low to moderate, proportional to per-user follows
Content volume	All public posts from all connected instances	Only posts from followed accounts
Content relevance	Low, includes off-topic and foreign-language posts	High, users curate their own feed
Moderation effort	High, must monitor and block entire instances	Low, handles individual account reports
Federated timeline	Filled with diverse posts from many instances	Empty or limited to followed accounts
User control	None, admin controls relay subscription	Full, each user chooses whom to follow
Server resource load	High CPU and disk I/O from processing many posts	Lower, scales with active user follows

You now understand the bandwidth and quality tradeoffs between relays and direct follows. For a small personal instance with limited bandwidth, direct follows alone work best. For a community instance that wants a lively federated timeline, a well-moderated relay can add value. Start with direct follows and add a relay only if your server resources and moderation team can handle the extra load. Use the Administration > Relays page to test a relay for 48 hours and review bandwidth logs before making it permanent.