Which Ports Should Be Open for an Email Server with High Security?

DE.

In order for a server to function as an email server, it must receive incoming emails from other servers or clients. To accomplish this, the server must have certain ports open that allow email traffic to enter and leave the server.

The question asks specifically about an email server with high security for incoming connections, which means that the server should only accept encrypted connections from clients.

Out of the options given, the following ports are commonly used for email traffic:

A. TCP 110 - This port is used for unencrypted POP3 (Post Office Protocol version 3) email traffic. It is not secure and should not be used for a high-security email server.

B. TCP 143 - This port is used for unencrypted IMAP (Internet Message Access Protocol) email traffic. It is also not secure and should not be used for a high-security email server.

C. TCP 161 - This port is used for SNMP (Simple Network Management Protocol) traffic, which is not related to email and should not be open for an email server.

D. TCP 993 - This port is used for encrypted IMAP traffic using SSL (Secure Sockets Layer) or TLS (Transport Layer Security). It is a secure option for incoming email traffic and should be open for a high-security email server.

E. TCP 995 - This port is used for encrypted POP3 traffic using SSL or TLS. It is also a secure option for incoming email traffic and should be open for a high-security email server.

Therefore, the correct answers to the question are D (TCP 993) and E (TCP 995), as these are the only secure ports listed that should be open for incoming email traffic on a high-security email server.