On the other hand, the commercial one is not too expensive (about 30 euros) and give you some options.
Thank you for your review.
Our free version also uses the queue to send e-mails.
It's done in a different way (there is no automatic processing on our free version) but you can configure a pause and start and stop the send process as you want (manually), even with our free version.
If anything goes wrong, AcyMailing will keep your e-mails in the queue and you will be able to resume the send process later.