To manage mailings of an event, go to the campaign section of that event. Below the statistics you can see which mailings you have sent, which are still in draft or which are scheduled. The overview also shows brief statistics.

If you want to view in-depth statistics, click on a mailing. The statistics show which recipients received your email, who watched it, which links the recipients clicked, which addresses bounced and who marked your email as spam. You can also see from which countries the recipients are coming. The statistics give you great insight in your mailing campaign and the success of your event.