I would like a definitive program logic description that takes into account all factors below to determine whether or not a chat user is 'pinged' using if I posted a message using "@joesmith" in a chatroom.

  1. If the person has never been in that chatroom (and consequently never posted in it), is it for certain that the person will not get a 'ping' in his/her chat inbox? (seems the answer is 'yes')

  2. What is the precise definition of the FAQ's "has been in the room at some point" or "recently active" (see quote in point 6 below)?

    • The time period: 1 day? 1 week?
    • How it is measured: since the last post, or since the last time the user enters that chatroom?
  3. The factor of being present in other chatrooms (listed in the avatar list for those rooms, even if grayed out) vs. not at all (left all rooms).

    For example, let's say @joesmith is not in any chatroom presently but has posted a message in that chatroom 45 days ago, will @joesmith sees something in his chat inbox the next time he goes to chat?

  4. Posted previously vs. currently in the room (i.e. didn't leave). @balpha in a comment says

    Note that you can only invite to a room that you're already in.

    What does it mean? Does it mean I have to remain present in the room, or does it mean I have posted messages in that room already? Does it matter how long ago I have posted?

  5. The role of some chat preferences: ignoring, "quicker notification" flag

  6. Different behavior ("super ping") if you are a moderator.

    For example, from the answer to a 12-year old question:

    You can't, unless the person's been recently active in the room you're currently in. Only moderators can use a "super-ping" feature to invite people to chat, even if they haven't visited it before.

  7. Whether or not I own the room

  8. Whether the person is a chat user (i.e. received a chat user id)

  9. Reputation of the user

  10. Status of the user (whether suspended or not)

  11. Other factors not mentioned above

I have reviewed:

Motivation: I'm trying to use chatrooms more to avoid unnecessary comments on older questions or older answers when I want to engage the post writers to discuss the topic rather than to improve the post (per SE guidance). I want to have some assurance of the other being 'pinged' and don't want to press the other into responding if he/she is not interested.

  • 4
    wrt 1. and 2. meta.stackexchange.com/questions/280412/…
    – rene
    Commented Feb 5, 2023 at 7:21
  • 2
    Its also worth thinking about whether the person wants to be pung, and not everyone might want to 'move' a topic over to a specific room Commented Feb 5, 2023 at 8:40
  • 3
    Whether or not @username works can be found out relatively easily - it works precisely for users offered for autocomplete. But if you want to make sure that somebody gets a notification, you can reply to one of their messages (if their posted in the room at least ones). And inviting a user creates a notification, too - on this per-site meta you can see an explanation with screenshots.
    – Martin
    Commented Feb 5, 2023 at 9:16

1 Answer 1


Here is what I know from years of chat experience.

In order for @JoeSmith to ping Joe Smith in a chat room, one of the following conditions must be met:

  1. Joe is currently in the room. In this case, it doesn't matter if Joe ever posted a message in the room.
  2. Joe is not currently in the room, however he did post at least one message in the past and it's not yet a week since he was last seen inside the room. Week being 7 calendar days, or 168 hours.

There is one less known rule, that for 48 hours since last being seen, short ping is also possible, e.g. @Joe will also ping Joe Smith, no need for the full name.


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