Common Pitfalls Building Email Agents (and Fixes)

Short summary

Email agents fail at infrastructure boundaries—at-least-once delivery, concurrency, and async action—not in prompts. This guide covers nine production pitfalls: self-reply loops (filter agent address), duplicates (dedup + thread locking), truncated messages (fetch full API), broken threading (reply_to_message_id), human corrections (30-60s cooldown), reply storms (per-thread budgets), and spam overhead (SMTP rules). Includes code examples and pre-launch checklist for safe launches.

• •Email agents fail at infrastructure boundaries (webhooks, concurrency, async), not LLM logic
• •Nine concrete pitfalls with code fixes: webhook filtering, dedup, locking, API fetching, threading, cooldowns, budgets, rules
• •Pre-launch safety checklist: implement all nine to prevent reply loops, duplicates, and runaway agents

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