Bursty Email in Exchange

I'm not sure how to describe our issue. Running SBS2011 w/ Exchange 2010. Our clients range from Office 2003 to 2013.

1. Not sure where in logs to look to see if there is an issue.
2. Until the each outlook client sends an email, the outlook client will not receive emails. After sending an email, it's like everything that was in the email queue gets pushed down to the receiver.
3. Each client says it's "Connected to: Microsoft Exchange"
4. I haven't checked with multiple users, but one user can not open Out of Office assistant on 2007. The warning is "Not connected to Exchange Server." Even though she can send emails.