But again, the point is that the users often don't know how badly their email is broken. Unless the user is actively expecting to receive an important mail aro

But again, the point is that the users often don't know how badly their email is broken. Unless the user is actively expecting to receive an important mail around a certain time and therefore likely to notice its absence, the failures are either quiet (messages dropped in junk automatically that may or may not be noticed by the recipient later) or totally silent (as with ISPs that drop mail they deem inappropriate entirely, without notifying either party). Even if someone is expecting a mail, as the experience with business customers I mentioned demonstrates annoyingly often, the failure to receive that email may be assumed to be the fault of the expected sender, not the recipient's own mail service.