Here's a list of standard ports to use for common server processes and services:

Port / Process/Service

21 FTP

22 SSH

23 Telnet

25 SMTP

53 DNS

80 HTTP

110 POP

119 NNTP

143 IMAP

443 HTTPS

465 Secure SMTP

585 Secure IMAP

587 SMTP alternate - Use if port 25 is blocked by the ISP

993 IMAP4 over SSL

995 Secure POP3

1433 MSSQL

2082 cPanel TCP inbound

2083 cPanel SSL TCP inbound

2086 WHM TCP inbound

2087 WHM SSL TCP inbound

2089 cPanel license TCP outbound

2095 Webmail TCP inbound

2096 Webmail SSL TCP inbound

3306 MySQL

3389 RDC - default Remote Desktop

5224 Plesk license

8080 HTTP - alternate port (also a Tomcat port)

8425 Horde

8443 Plesk