Tolerance for Email Outages?

Oddly enough, though many users will tell you that email is more important than voice, they also seem more tolerant of email than voice outages.

Most organizations put up with periodic outages and most seem to tolerate that state of affairs.

But email seems to benefit from different expectations, in particular the store and forward use model.

The fact that voice mail is the same sort of experience doesn't seem to detract from the possibility of a synchronous session at least part of the time.

Curious, don't you think?