When did you last do a battery pull or "quick pull" to clear chache/memory? It may be that simple.
How many email addresses do you use on the phone? Is it only one email address that is delayed, or all?
Battery pull doesn't work, I've done that several times.
The phone uses two email addresses, and both have that problem, though not always at the same time.
OK--bear with me as I run through some possible scenarios that may or may not apply - but it may jog something in your thinking...
Are you traveling in and out of a strong/weak signal area? That may cause the email to be delivered in batch when the phone reconnects with the network. Or is the phone being shifted to wifi only or airplane mode for periods of time?
Are these two email addresses the same domain or different? Is either one your vzw blackberry email?
You could try deleting the email account(s), rebooting the phone, then adding the accounts back in to see if they function any better.
I see what you're getting at, and I think it's in the right direction, but it's not any of that. I have wifi and the cell network on all the time. And the place where I'm most likely to get emails is at home, where I get two bars of a signal at most. At my office, where I get 5 bars all the time, I almost never get emails. Of note, though, I do not have a wifi network that I connect to at work.
The two email addresses are different domains, one is my own domain, and the other is a gmail address.