There is Exchange with the following configuration:
Exchange 2013 - 6 Mailbox/CAS.
number of users - 4500
Client Connect - RPC/HTTP
Outlook Anywhere - outlook.mycomp.com
Other - mail.mycomp.com
smtp - smtp.mycomp.com
pop3 - pop3.mycomp.com
Tell me which HAproxy configuration is better to use?
You could take a look on https://www.haproxy.com/documentation/haproxy/deployment-guides/exchange-2010/