Post Office Protocol(POP) is used by email clients to retrieve email messages from remote email servers.
The current standard is version 3 of the protocol (POP3).
Most POP3 clients generally delete messages from the server after retrieving them and storing them locally.
The default port number that a POP3 server listens on is 110.
The server requires a username and password to authenticate a client.
TLS/SSL are cryptographic protocols for secure communication over computer networks.
They are based on the exchange of X.509 certificates and public keys for encrypting and decrypting messages.
Digital certificates are issued by a certificate authority (CA) trusted by both parties involved in the communication.
This directly affects the quality of your service, because your clients or employees rely on email every day.
If the server uses TLS/SSL security, it is also important to monitor the certificate expiration date.
