v2.2.1

Added

• Configurable SMTP and cron-lock timeouts.
• A cross-process cron lock (MySQL GET_LOCK), so batches cannot overlap.

Changed

• WordPress Plugin Check compliance: output escaping, ABSPATH guards and safe redirects.
• Lower memory use: email bodies load one at a time instead of all at once.
• The attachment directory is protected through the WP_Filesystem API.

Removed

• Development error_log / print_r calls, and the %i placeholder for WordPress before 6.2.

Fixed

• SMTP accounts are no longer blocked mid-cycle by the send_interval check.