E-newsletter is sooo slow in sending emails to big lists

My hosting server is capable of sending 60 emails every minute but the it took a long time to send emails using e-newsletter compared to other plugins.

It took me over 12 hours to send to a list of 6000 members; so less than 10 emails a minute. this is extremely slow. Is there anyway to fix this.
I already put wait "1" second between each email in the settings but did not help. I tried putting 0 and still did not help