<![CDATA[Email remains a primary communication channel across academic, professional, governmental, and personal domains. Despite its widespread adoption, conventional email infrastructure continues to exhibit fundamental security vulnerabilities, including susceptibility to phishing attacks, unauthorized message interception, identity spoofing, and unintended data disclosure. Although Transport Layer Security (TLS) has become the de facto standard for securing email transmission between clients and servers, its protection is confined to the transport layer and does not extend to message content stored on mail servers or processed by third-party providers. This study presents an empirical evaluation of OpenPGP-based end-to-end encryption implemented through Mozilla Thunderbird as a mechanism to address the limitations of transport-layer-only security. The research employs a comparative experimental design, contrasting standard TLS-only communication against OpenPGP-encrypted communication across multiple message size scenarios using packet-level analysis via Wireshark. Evaluation parameters encompass confidentiality, message integrity, sender authentication, payload visibility in TCP stream analysis, and transmission overhead across varied email payloads. The results demonstrate that while TLS-only communication still exposes identifiable SMTP metadata during packet inspection, OpenPGP transforms email content into high-entropy ASCII-armored ciphertext that resists direct interpretation even under deep packet inspection. Furthermore, cryptographic digital signatures successfully verified sender identity and ensured message integrity across all tested scenarios. Although OpenPGP introduces measurable transmission overhead averaging approximately 117% depending on message size, the security benefits substantially outweigh this trade-off. These findings establish OpenPGP as a robust and practical solution for enhancing end-to-end email security in modern communication environments.]]>
