Can the send/recieve times be configured to be performed at specific times and at no other times for the users? For example emails are only received at 10:00am and 3:00pm EST. Thank you for your time concerining this question.

No the send and receive connectors in Exchange 2007 can't do that

But you could probalby schedule a batch file to start/stop the services during each of those time windows. Not sure why you'd want to though as it would create lots of NDR situations.

Per my knowledge, theres no feature which can do it in the exchange natively, and as Jeff said, itll produce NDRs for some messages which cant reach to destination