If there is a fire and a risk to life, you don't want any delay.
replyThen don't send an email? Emails are async in the first place.
replySometimes it's the only thing you have available. Like IDK during a fire in a basement server room, where the only connected device available is a laptop with wired connection and an open inbox.
replyBecause you know, you tried IM but "sekhurity reasons" demanded passkeys or 2FA with your phone that's not connected. Sorry, getting off-topic here.