I have a high count of failed messages

I’ve got domain throttling turned on and I limit the batch size. I have 5000 subscribers to send to and emails are being sent in 140 message batches. But each batch is failing 130 emails and only sending 10 messages at a time every 130 seconds. You can imagine that it takes forever to send merely a few thousand messages. What is the best way to maximize message throughput without getting you blackballed? And if only 10 messages out of 140 are sent, why can’t PHPList retry in 5 seconds instead of waiting the whole 140 second period?