Evan Prodromou

So, if we know at the time the activity is received that it is unacceptable for some reason (spam, etc.) then we can send a 4xx HTTP code, most likely...

In discussion, we think a 403 Forbidden code may be useful when the sending actor or server is blocked and not authorized to ever send activities to this inbox. A...

I think it makes sense in the case where a sender expects some sort of side-effect from the activity, such as: - `Like` -- the `Like` activity should go into...

> After all, with open-source ActivityPub servers spammers can just set up their own captive "test lab" to try attacks against without needing to get explicit confirmation) This doesn't make...

This is probably a useful feature, especially for services concerned with tracking GDPR compliance of downstream processors. However, it's not currently covered in ActivityPub, and it would probably be a...

I got the same thing.

We should have a Primer page on using `context` for conversations. I'll add it at https://www.w3.org/wiki/ActivityPub/Primer/conversations .

Blocklists and the #fediblock hashtag have been useful on the fediverse for this problem so far. In particular, for servers that were set up specifically for mass harassment.

[Greylisting](https://en.wikipedia.org/wiki/Greylisting_%28email%29?wprov=sfla1) might also be a good technique here. (I'd appreciate any guidance on a better term for this technique. "Delay listing"?) This is a technique for temporarily rejecting messages to...

[Shadow banning](https://en.wikipedia.org/wiki/Shadow_banning?wprov=sfla1) is another technique that might be helpful. Showing a brigader their comment or reply in a list of replies, even if no one else can see them, might...