My hosting enable to send 750 e-mails per hour.
I have about 800 subscribers.
By PHP I filteringed system the emails addresses and group them by mail server.
Not sure what you mean. But assume you send one mail per day to your subscribers...
Divide the job into 12 hours. So send 800 / 12 emails every hour. Or better yet, have a CRON job that runs every minute and sends out 2 emails per minute. That way it streams out nicely for the rest of the day and you won't get banned by the email providers or your hosting provider.
This entails a little more programming. You can setup a queue or something and have your cron job pull out email from the queue.
On the other hand, if you have to send emails to all those people on multiple times per day, then the queue system would still work, and you can send out mail a little faster.
In any event, assume you have a max of 750 emails per hour, that would give you a max of 12 per minute.
Can you to split listing into 2 parts? Half and half for example and send it in two different hours. Uncertain about your particular scenario because you didn't say which server and which software you utilize to send it. Generally speaking, most SMTP servers have the capability to re-try and resend the message multiple times so if it didn't experience when, then it will re-try once more for some time until it quits. Even if it fails for an hour, if you do not deliver anything else it could prosper at the next hour.
Thank you so much Vitaly and Ericson for you great answers and for helping me out! Yes... I can actually split my listings. And sending email is a lot easier and faster now.