My client ask if he can send more than one newsletter at the same time with Entreprise Edition.
I personally think that, yes you can, but you have to do it consecutively and you will still be limited by the mail server limitation and the queue.
I also guess that the first mailing sent will pass first and any other after will start to be sent after the first one is completed.
Can you tell Acymailing to sent a percentage of say 2 mailing at the same time?