Posts in Mastodon can be set to automatically self-destruct after a certain time period, with exceptions made for posts you want to keep. Here’s how to do it:
- Log in through your server’s website
- Go to Preferences > Automated post deletion (on mobile you may need to click ☰ first)
- Choose the Age threshold to set how long posts are around before they’re deleted
- Set the exceptions for posts you want to keep
- Tick the box at the top marked Automatically delete old posts
- Click the Save changes button
If you want to stop deleting posts automatically, UN-tick the box and click the Save changes button.
I activated this but it hasn’t deleted posts that are way past the threshold. What’s going on?
If servers are busy, they create queues of tasks to work through. Automated deletion tends to go at the back of the queue, so it may take longer to happen than other tasks. If the settings are correct and it’s way past the deadline for the deletions to happen, ask your server’s admin for advice.
How does this affect server running costs?
When this feature is discussed, the issue of server running costs is often raised.
On the one hand, automated stuff always adds extra tasks for the server to carry out. On the other hand though, it would mean the server doesn’t have to store as much data so it would save money on storage costs, especially if the deleted posts have media attachments. It would also reduce storage for any servers that have federated the posts being deleted.
You would have to speak to your server’s admin to find out exactly how it affects their setup, as different servers may have different resources available.
I asked a couple of very large server admins for their thoughts on how this balances out. Both of them said the added tasks were insignificant compared to everything else the servers have to do. Both of them also said deleting posts (especially posts with media attachments) saves storage, but one of them added that there may be fees to be paid if the deletions happen for very recent posts. On their server, it would be cheaper to only delete posts more than 90 days old, and leave any newer posts intact.