Be careful—you’re getting a few things mixed up.

Lemmy is software built around the concept of “communities.” A Lemmy user isn’t focused on what individual users write; rather, they are interested in what is being posted within the specific communities that interest them!

Therefore, it makes perfect sense that you wouldn’t see content from Mastodon users if they haven’t consented to being visible to you.

In fact, if a Mastodon user chooses (via opt-out) to post within a Lemmy community, you will see that content—provided that you are also subscribed to that community.

Conversely, a Mastodon user will generally see your content in the following three scenarios:

1. If they follow you, or if they follow someone who follows you.
2. If they follow someone who “reposts” (or “retweets”) your content.
3. If someone on your instance follows you, or follows someone who “reposts” your content.

Note that when I say “someone who reposts your content,” that “someone” could be another Mastodon user, but it could also be the Lemmy community where you are posting. In effect, these communities function as special ActivityPub users; Mastodon perceives them as such—for instance, the community https://lemmy.world/c/fediverse appears to Mastodon as the user @fediverse@lemmy.world.

Bridging the “social-verse” (social networks) and the “forum-verse” (discussion forums) has always been an important goal for me. I’ve made an effort to inform Mastodon users about this through posts like this one: https://www.informapirata.it/2024/01/02/mastodon-tips-how-to-use-friendica-groups-forums-and-lemmy-communities/

…but it’s clear that Mastodon users—and, more importantly, Mastodon administrators—aren’t particularly interested in connecting their users with communities on platforms like Lemmy, PieFed, MBin, or NodeBB. Fortunately, there are some positive developments on the social side:

• There is an app for Mastodon called “Raccoon for Friendica” that makes managing groups easier for Mastodon users. (It’s called “Raccoon for Friendica” because it originated for Friendica, but more importantly, its developer previously worked on an app for Lemmy.)
• A fork of Misskey called “Catodon” offers excellent support for ActivityPub groups, potentially ushering in a new era that bridges the “socialverse” and the “forumverse.”

There are also interesting updates on the forum side: NodeBB now allows administrators to forcibly “move” initial posts into a specific category (in NodeBB, “communities” are referred to as “categories,” but they still function as ActivityPub groups). While this move isn’t visible to other instances within the “forumverse” (such as Lemmy or other NodeBB instances), it is visible to “social” users—because the “category” effectively “boosts” the moved post, allowing social users who follow that community to see it.

I’m not familiar with Piefed, but it would be great if the Lemmy developers took two steps:

1. Introduce a feature similar to NodeBB’s, allowing posts to be moved within a community.
2. Find a way to make this move “visible” across the board—so that it’s not just users on the local instance or those on social platforms who see the change, but also users on other “forum” instances!

However, there could also be negative developments. The most likely risk, in my view, is that the “little dictator” (Mastodon) might decide to implement ActivityPub groups in its own idiosyncratic way—one that is, predictably, incompatible with the “forumverse.” Given how they implemented “quote-retweets,” I’d say that bad news is more likely than good news…