For me, a 'pop-up' window appears straight away and I read it regardless, some people are better at this than others (reading PMs swiftish), moderators included.
I'm surprised people don't see this stuff straight away as usually it shows itself in no uncertain terms in the form of a 'pop-up' as soon as it's sent.
As said, replies are at the receiving person's discretion, but you can see that they have read it because it moves from 'outbox' to 'sent' etc, no dramas. Just get perplexed when it sits in the 'outbox' for a while or a week or so.
Yes, before the wise guys

Added a poll to be sure.
