Port 995 is the designated port for secure POP3 communications, also known as POP3S or POP3 over SSL/TLS. When configuring an email client to retrieve emails securely via POP3, it should be set to use this port, which facilitates encrypted communication to prevent eavesdropping. Port 110 is used for non-secure POP3 connections. Port 587 is for submitting emails via SMTP securely using STARTTLS. Ports 143 and 993 are typically used for the IMAP protocol, with the latter being the secure version (IMAPS). Port 25 is used for unencrypted SMTP.