Iredmail, web system requirements?

Question

Debian

Good afternoon.
I want to put into production a mail and web server running debian. There are about 200 mailboxes and one web project with about 150-300 users per day.
What percent and how much memory is better to use for this business? Yes, I read the Internet, but everything is blurry everywhere, so it would be interesting to know the opinion of specialists.
Thanks a lot, everyone