Jacob is worried about sniffing attacks and wants to protect his SMTP transmissions from this attack. What can he do to accomplish this?

An SSL/TLS certificate enables encrypted SMTP transport via SMTPS (port 465) or STARTTLS (port 587), wrapping the email session in an encrypted channel so that any packets captured by a sniffer on the network cannot be decoded. This directly counters sniffing attacks by ensuring confidentiality of data in transit. Without this encryption, SMTP credentials and message content are transmitted in plaintext and are trivially captured.

EFS (Encrypting File System) encrypts files stored on a local disk volume and provides no protection for data actively transmitted over a network, leaving SMTP traffic fully exposed to sniffers.

A proxy server routes traffic through an intermediary for access control or caching purposes but does not inherently encrypt the SMTP session between endpoints, so sniffers on the path can still capture plaintext data.

A firewall enforces network access control policies and can block unauthorized connections but does not encrypt the content of permitted traffic, offering no protection against sniffing within an allowed network path.