How does an email travel through the ecosystem?

An email's journey starts when you hit send. Your **ESP** queues the message, signs it with DKIM, and transmits via **SMTP** to the recipient's **mailbox provider**. The message travels through multiple servers, each adding headers documenting its path.

The receiving **MBP** performs extensive checks: **DNS** lookups verify SPF authorization and DKIM signatures, DMARC policy determines enforcement, blocklist queries check **sender reputation**, spam filters analyze content, and engagement history influences scoring. This happens in milliseconds.

Based on these checks, the **MBP** delivers to inbox, spam, or rejects entirely. The decision gets logged and affects future reputation. Bounces return to your **ESP**. The recipient's engagement (opens, clicks, complaints) feeds back into reputation systems, completing the cycle that influences your next send.