[silentfish]

If the matter is time-sensitive then I need to ask whether the user is available or not to provide an answer.

  u1: Hi, can you switch to the alternate server, the main one is crashing

  [... 12 hours later, when the problem has already been resolved]

  u2: Sure thing, let me do it.

  u1: STOOOOOOOOOP!

[basseq]

Or, for sensitive context, "hey, is this alert about to pop up on a projector in front of 50 people?"

[lloeki]

If it's sensitive I always phrase it in a way that would make the sensitive part truncated due to notification space being limited.

[icebraining]

IMHO, a better approach is for u1 to say "nvm, john's got it" before u2 replied.