I've had this problem for a few months now and have been happy enough with my "fix" (below.) Recently I've been bothered by my battery life and have been trying to figure out how to resolve this issue.

Basically -- when I am at home or my office and I leave wifi set to "always-on" I stop getting email. I can't perform manual syncs or have push emails come in. It constantly looks like there is zero new messages. This happens with both my exchange account and gmail account. When I switch back over to EVDO it takes between 5 and 60 minutes but it starts catching up and bringing in new emails.

My "fix" has been to leave wifi set to "sleep when phone sleeps." This makes the phone bounce between wifi and EVDO based on screen-state. It fixes my email problem but drains my battery even faster than normal. Anyone have any ideas about what I can do?