I got this PM from u/reddit 5 days ago. I think it's relevant to all of us, not just people who moderate dormant subreddits, so I'm sharing it here. The ModNews link in the message gives more info on what "dormant" means.

#Automated message from reddit begins below:

Hello,

We are reaching out because you moderate 1 dormant subreddit(s) that qualify for removal.

When subreddits have had no activity, we periodically remove them to make space for new communities. For more information about what this means please visit our r/ModNews post.

Subreddits that you moderate that qualify for dormant removal include:

• mystyrnile

If you would like any of these subreddits to remain on the platform, you may opt out by banning u/SubredditPurge from your dormant community. This will signal to us that you're aware that your subreddit is dormant and have reason to keep it. While you're at it, if you'd like to grow this community, you might want to take a look at our tips for growing a new community.

Within the next two weeks, we will be removing these dormant subreddits. If you would like your subreddit to remain on the platform, please opt out as soon as you can.