Encrypting SMTP and IMAP connections is important because it helps to protect the confidentiality and integrity of sensitive email communications.

SMTP (Simple Mail Transfer Protocol) is the standard protocol used for sending email messages, while IMAP (Internet Message Access Protocol) is the recommended protocol for retrieving email messages.

The email client of the sender (1) uses SMTP protocol to send out messages to the submission service (email server) of his Email Service Provider (ESP). For POST residential customers (@pt.lu), the submission server’s hostname is smtp.pt.lu .
POST email service infrastructure manages delivery of the sender’s message to the recipient’s ESP’s email server (2) using also protocol SMTP.
Finally, the message is delivered into the mailbox of the recipient and the recipient may retrieve the message using IMAP or POP3 Protocol.

Often, these protocols (SMTP, IMAP, POP3) transmit email messages in plain text format, which means that anyone who intercepts the traffic can read the content of the messages and even worse, depending on your configuration, the sniffer can intercept your password.

Encrypted SMTP and IMAP connections, on the other hand, use secure protocols such as SSL (Secure Sockets Layer) or TLS (Transport Layer Security) to encrypt the email traffic between the email client (such as Outlook or Apple Mail) and the email server. This ensures that the email messages and any attachments are transmitted in an encrypted format, making it difficult for anyone to intercept or eavesdrop on the communication.

Encrypting SMTP and IMAP connections is especially important when sending or receiving sensitive information, such as financial or personal data. Without encryption, this information could be intercepted and read by cybercriminals or other unauthorized parties, leading to identity theft, financial fraud, or other forms of harm.

In summary, using encrypted SMTP and IMAP connections is important to protect the confidentiality and integrity of email communications, and to ensure that sensitive information is kept private and secure.

For these reasons, we enforce encryption on SMTP & IMAP (as well as POP3) connections.