Worked on PHPMailer/PHPMailer, focusing on backend and email development using PHP to address a critical issue in S/MIME header encoding. Delivered a targeted bug fix that stabilized the encoding of MIME headers in signed messages, particularly for long lines, preventing header corruption and ensuring proper boundary handling. The approach involved refining the encoding order and improving the reliability of the S/MIME workflow, which reduced the risk of misinterpretation in email delivery. No new features were introduced during this period, as the primary goal was to enhance security and maintain repository stability through precise, security-focused engineering improvements.