I typically send out newsletters that reach roughly 860 different emails, however, it is sending out very very slowly. I’ve checked with my host and ISP and I’m not being throttled back on my speeds as well as set the plugin to a very high setting (1000 per hour max). After submitting a newsletter to send, I watch the mail queue, and I see that the newsletter emails populate it [the mail queue] very slowly.
All in all it seems it takes upwards of 4-5 days for all my emails to simply reach my mail queue in order to send.
Gmail lets only 500 email per day. It’s an incredible low limit for a newsletter. 500 emails per day divided by 24 hours is 20 emails per hours, this is the limit you should set on main configuration panel.