Hello kernelpaniker

I am also on a shared server and have mine site to 300 which seems to work well.

Unfortunately I can't really help you with the maximum specs for maximum mailage. I would suggest that your hosting company are the best people to ask as I am sure that they know what their servers can do.

Obviously everyone here on Unity would have a different set of statistics when it comes to servers, CPU, RAM and members.

I have approx 2500 members on my site with the cron job set see more to pop out emails every 30 minutes. So that is 300 peeps every half hour.

Hope this helps you in some way. Am curious to see what everyone else says.