v.2.1.0

Added

• Grouping mode for bounce report: entries can now be grouped by sender address (mailfrom) when GROUP_BY_FROM="true" is set in config.
• HTML group headers include sender and bounce count, styled with .grouphead class.
• Visual improvement: added light gray background (#e9e9e9) to .grouphead rows for better readability.
• Fully consistent HTML escaping of all dynamic content to avoid rendering issues.
• New sender marking logic to identify bounced emails as resent (known senders sending from external domains) or spoofing (possible impersonation from internal domains).
• Introduced configuration flags RECIPIENTS_CHECK and SPOOFING_CHECK to control sender verification and spoofing detection.
• Added support for maintaining a known senders list via the helper script postfix-build-submission-recipients.sh.
• Added separate documentation file SENDER_MARKING.md explaining the marking logic and setup in detail.

Changed

• Improved performance of postfix log parsing by replacing external date calls with inline Time::Piece Perl code.
• Added explicit year handling in log timestamp parsing to ensure correct epoch comparison.
• Optimized generate_html_report() function: moved all log parsing and HTML generation to a single awk block.
• Report generation time reduced from several minutes to a few seconds for large log files.