When you send out an email campaign the emails are all queued up from all accounts and sent together by order received. This means that there might be a delay between the time you click “Mailout” and the time the email is actually mailed out. Remember you can always check the state of your emails by clicking the Queue link or button for that campaign. If there is something in the queue you’ll be able to review it.
We are currently bolting on a brand new email messaging system that will ship emails at a much (much) faster rate than the current system. We’ll have it ready to go this week.