This community is experimental. Essentially, it boosts posts from Mastodon users into lemmy, allowing their content to appear here, still attributed to them. This is better than me reposting stuff from there I think, but please be aware of how Lemmy and Mastodon do and don't co-operate:
• Originally, I wanted the posts to be mainly text-based, simply because, in terms of efficiency, accessibility and credit, the original text is better than the screenshot of text you might see at the MicroblogMemes or BestOfMastodon communities. It turned out though, that screenshots do actually provide advantages that are difficult to replicate in the UI, and this community has ended up being mostly image-based.
• If you reply to a post, your instance will send one copy to me (to federate to other lemmy instances), and one copy to Mastodon, meaning that the original author will see your reply, and you'll be able to view your reply there if you click the multi-coloured Fediverse symbol next to the post. If you reply to a reply, that typically isn't sent to Mastodon. If you delete your comment, then my software will take care of deleting it on other Lemmy instances, but your instance doesn't send a 'Delete' to Mastodon, so it'll still be visible there. If you've ever had an inbox notification for a reply that it turns out has been deleted, you will have seen this behaviour for yourself. There's not much I can do about it, but if it concerns you, I've seen edits go through, so overwriting your content with [deleted] or something is maybe an idea.
• Whilst your reply will be sent to the originating Mastodon instances, it isn't sent to the author's followers on other Mastodon instances (lemmy currently doesn't expect users to have followers)
• If your reply includes an inline image, then that isn't rendered on Mastodon (which expects images to be attachments, and doesn't convert them as Lemmy does when they come in the other direction)
• I tend to boost things as I see them on Mastodon. Sometimes I bring some of the existing comments there through as well, but not always, and wouldn't typically go back for more after the post has been made. However, the software does follow some people on Mastodon, so replies made on Mastodon after the post has appeared here will also come through. They'll be stripped of the annoying @ links, but not of hashtags (just because a reply could be "that's a great #dadJoke" or something)
• A major limitation is that some Mastodon instances have Authorized Fetch turned on - updates from those users can't be posted on Lemmy because it doesn't sign the GET request to fetch the user's details. Examples of instances with AF on: infosec.exchange; tech.lgbt; universeodon.com
Other notes:
• It's called 'tails' for 2 reasons. One is that 'tailing' someone is a synonym for following them. The other is that this community flips the idea of a User following a Group, and has a Group follow a User in a head/tails kind-of way. (Well, okay, 3 reasons - the last being that naming stuff is hard, okay?). It's unrelated to the Operating System
• Replying to this post is the best way to get in touch with me if you want. I'm 'freamon' at endlesstalk.org and lemmy.world, but a reply here will send a notification to my phone.