I have noticed that there are times when I am unable to '@' tag a user or trigger the auto-complete popup. Sometimes, even when I type @username in a comment, SE automatically removes the tag when posting. Is this a bug, or are there specific conditions for tagging users?

1 Answer 1


It's explained in horrific detail in How do comment @replies work? but the gist of what you need to know here are thus:

  • If there are only two users leaving comments, it is not necessary and the system will know to notify the other party. Therefore it will strip it as a courtesy of clean comments.

  • Use the @ notation when there are more than two users leaving comments on the same post.

  • If you need to @ ping another user leaving comments on the same post, don't do it at the front of your comment. Work it in naturally somewhere in the middle or end.

  • The owner of the post is always notified and it's pointless and noisy to @ ping them in the comments.

  • That last point is obsolete: @-addressing the owner (i.e. you in this case) will be stripped from the comment. This is fairly new and probably to reduce noise. This comment started with "(at)random" when written.
    – Daniel Beck Mod
    Commented Nov 29, 2011 at 19:22
  • On a post with multiple users, you may see some @ ping the OP at the head of the comment, out of some convention even if they don't need to
    – random Mod
    Commented Nov 29, 2011 at 19:28
  • Ah yes, if there are other possible recipients, it's kept in.
    – Daniel Beck Mod
    Commented Nov 29, 2011 at 19:32

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