SysPad › Examples › Distributed email service
Distributed email service
Mail API → Mail Processor → spam/virus filter → delivery queue → a handler that fans out to attachment storage, metadata, search indexing, and SES for SMTP delivery.
Spam filtering as a mandatory gate before anything reaches the delivery queue.
- Throughput: 3,000 req/sec
- First to saturate: Search Index
- Estimated cost: $838k/mo
How it works
- Spam/Virus Filter
- The mandatory gate: nothing reaches the delivery queue until it clears spam and virus checks. It is the slowest step on the path (40ms) precisely because it is the one that must not be skipped.
- Delivery Queue
- The send returns once the mail lands here. Everything after - attachment write, metadata, indexing, the SMTP send itself - happens as the handler drains the queue, so a slow SES send never blocks the sender.
- Delivery Handler
- Fans one dequeued message out to four sinks at once: attachment storage (only when there is one), the metadata store, the search index, and SES for the actual send.
Request flows
Send an email
- Client
- Mail API
- Mail Processor
- Spam/Virus Filter
- Delivery Queue
- Delivery Handler
- Attachment Storage
- Metadata Store
- Search Index
- SMTP Delivery