Campaign E-mails Didn't Send (or is it really, really slow)

I launched a campaign this morning at 7:00AM with 2500 contacts in it and only 370 e-mails were sent (90 minutes later). Any thoughts? It send 370 right away and none since then so I don’t think it is slow.

It looks like everyone it didn’t send to is marked Unengaged Marketable. But I thought that wouldn’t block e-mails from a campaign?