Python SMTP Bulk Sender Optimization & Debugging Expert Needed

I need an experienced full-stack developer (not AI-generated coding services) to urgently debug and optimize an existing Python SMTP sending script. The script currently sends emails using SMTP with BCC batches (95 emails per account), account rotation, and parallel processing. It was working correctly before, but the sending speed has become extremely slow, and I need someone who can quickly detect the bottleneck and fix it directly. Requirements: * Strong experience with Python and SMTP/email delivery systems * Experience with multithreading, multiprocessing, async optimization, queues, and network debugging * Ability to analyze existing code fast and identify performance issues * Must be able to work immediately * Deadline: within the next 3 hours Important: Please do not apply if you rely mainly on AI-generated coding or generic debugging. I need a real developer who can manually inspect the system, understand the architecture, identify the root cause, and optimize it properly. When applying, please mention: * Your experience with SMTP bulk sending systems * Similar optimization/debugging work you have done * Whether you can start immediately If you read the description carefully, start your proposal with: "SMTP_DEBUG" I will share the script directly with the selected developer.