For port mapping (publishing your servers)
As i undestood, you want to access HTTP/HTTPS/IMAP from outside by standart ports and SSH by non-standart. So...
1) Objects > Services
Make service ssh-xxx00 with destination port xxx00
Make service groups ext_mail_server with imap, pop3, smtp (all services what you need) and ssh-xxx00
Do the same for web servers (group ext_web_server)
2) Rules > IP rules
# mail server
SAT wan/all-nets core/wan_ip ssh-xxx00 (SAT: new dest = lan_mail_server, new port = 22)
SAT wan/all-nets core/wan_ip ext_mail_server (SAT: new dest = lan_mail_server)
Allow wan/all-nets core/wan_ip ext_mail_server
# web server
SAT wan/all-nets core/wan_ip ssh-xxx02 (SAT: new dest = lan_web_server, new port = 22)
SAT wan/all-nets core/wan_ip ext_web_server (SAT: new dest = lan_web_server)
Allow wan/all-nets core/wan_ip ext_web_server
If you want to have access from internal network (LAN) to wan published services, make additional rules
# mail server
SAT lan/lannet core/wan_ip ssh-xxx00 (SAT: new dest = lan_mail_server, new port = 22)
SAT lan/lannet core/wan_ip ext_mail_server (SAT: new dest = lan_mail_server)
NAT lan/lannet core/wan_ip ext_mail_server
# web server
SAT lan/lannet core/wan_ip ssh-xxx02 (SAT: new dest = lan_web_server, new port = 22)
SAT lan/lannet core/wan_ip ext_web_server (SAT: new dest = lan_web_server)
NAT lan/lannet core/wan_ip ext_web_server