How can i get list to whom i sent an e-mail?

Hello,i just sent out a e-mail campaign with initially 1.500 recipients.
In the admin section it is shown that only 400 e-mail were actually sent.

Is there a possibility to get a list with these 400 recipients?

My thoughts are, that i want to erase these 400 from the initial list and to
send out the e-mail with 1.100 recipients through another system.

Thanks for your help.
Greets from Germany,
Stefan Fischer