[rustmailer]

Bichon connects to the IMAP server via IMAP and uses a sync interval, for example 10 minutes. Every 10 minutes, Bichon downloads emails from the IMAP server to the local machine, then stores and indexes them. If an email is permanently deleted within that interval, Bichon has no way to detect it. That is indeed how Bichon currently works.

[pabs3]

IMAP has mechanisms to notify clients about incoming emails (IIRC IMAP IDLE), have you considered implementing those?

[rustmailer]

IMAP IDLE tends to be unstable and unreliable in real-world deployments, especially for long-running background services. It also introduces significant operational and implementation complexity, which makes it harder to maintain and reason about. For a system like Bichon, a simpler diff-based approach is usually easier to operate and more predictable.