Honestly, whoever has an idea for a spam detection measure for Mastodon, and by that I do mean an implementation, get in touch with me, I'll pay for it.
I've been thinking about solutions for the past few days but the more I think about them the more they appear pointless.
Defining an account as suspicious when it has no local followers can be circumvented by just pre-following them, using account age can be circumvented with sleeper accounts, blacklisting URLs does nothing when the spam does not include URLs, checking for duplicate messages sent to different recipients can be circumvented by randomizing parts of the message...
@Gargron We don't need to start from scratch on each instance. Tools like rspamd and spamassassin come around with pre-trained sets.
That means we can make community efforts to build a repository of spam messages in order to pre-train filters.
And of course it's not super effective, but if we really want spam protection, we have to start somewhere.
@sheogorath @gargron I think Mastodon/ActivityPub also benefits from being able to build a reputation on instances, rather than individual users. Older instances, or at least ones that don't remove spambots when reported, can accrue a poor reputation and their incoming messages can be more highly scrutinized. And instance admins will be incentivized to decrease spam (the same way email sending servers are) so that their legitimate outgoing messages won't be ignored.
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