Is IMAP polling still reliable in 2026?

Yes, IMAP remains a standard and widely supported protocol. Reliability depends on correct UID tracking, handling UIDVALIDITY changes, and respecting server rate limits. It is slower than webhooks but entirely viable for low-volume or internal use.

How do I stop duplicate webhook deliveries from creating duplicate records?

Extract a stable message identifier, store it in a unique-constrained table before processing, and return 200 immediately if it already exists. Then process asynchronously. This makes repeated deliveries harmless and is the standard idempotency pattern.

What happens if my webhook endpoint is down?

Most providers retry for a limited period, then stop. Messages sent during a long outage may be lost from the webhook stream. Mitigate with a dead-letter store, monitoring, and a periodic reconciliation poll against the mailbox or API.

Can I use a disposable inbox to test inbound email handling?

Yes, for development and testing. A temporary inbox with an API lets you send test mail and read it programmatically without polluting a real mailbox. It is not suitable for production delivery, because inboxes expire and addresses are not permanent.

Should I verify webhook signatures?

Always, if the provider supports it. Signatures prove the request came from the provider and was not tampered with. Use a constant-time comparison and rotate secrets with an overlap period so old and new signatures both validate during rotation.

Receiving Email in Your App: Polling vs Webhooks

You need your application to receive email — signup confirmations, support replies, OTP codes, or inbound parse data. The two common architectures are polling an IMAP mailbox on a schedule and receiving inbound parse webhooks from an email provider. Polling is straightforward to reason about but adds latency and load; webhooks are near-real-time but require careful handling of duplicates, retries, and failures. This guide explains how each works, what breaks in production, and how to combine them safely.

How receiving email in your app actually works

Email delivery is store-and-forward. A sender's mail server connects to your domain's MX record, and the receiving server accepts the message and stores it in a mailbox. Your app then needs to get that message out of the mailbox. There are two fundamental ways: ask the mailbox repeatedly (polling), or have the mailbox tell you when something arrives (webhooks or push notifications).

Both approaches ultimately read the same underlying message store. The difference is who initiates the conversation and how quickly you learn about new mail.

IMAP polling in plain terms

IMAP is a standard protocol for reading a mailbox. Your app opens a connection, authenticates, selects a folder (usually INBOX), and asks for new messages — often using SEARCH UNSEEN or UID FETCH since the last seen UID. You then parse the raw MIME message and mark it as read or move it.

Polling means repeating that check on a timer: every 30 seconds, every minute, or every five minutes. It works with any IMAP server, including a mailbox you control, and it does not require a third-party email API.

Inbound parse webhooks in plain terms

With an inbound parse service, you point your domain's MX record at the provider. When mail arrives, the provider parses the message (headers, body, attachments) and sends an HTTP POST to a URL you specify. Your endpoint receives structured JSON or form data and processes it.

This is the model used by transactional email providers and by services like MailboxTemp's public JSON API, which exposes received messages for programmatic access. The key difference from polling is that the provider pushes to you rather than you pulling from it.

Polling vs webhooks: a side-by-side comparison

Aspect	IMAP polling	Inbound parse webhooks
Latency	Up to one poll interval	Typically seconds
Infrastructure	You run a scheduler and IMAP client	You run a public HTTPS endpoint
Auth model	Mailbox credentials or OAuth	Shared secret, signature, or IP allowlist
Failure visibility	Your logs only	Provider retries and delivery logs
Duplicate risk	Low if UID tracking is correct	High — retries can repeat a POST
Ordering	Usually chronological by UID	Not guaranteed
Local development	Easy with a test mailbox	Needs a tunnel or mock
Cost model	Mostly your compute and connections	Per-message or per-request pricing

When is polling the right choice?

Polling is often the pragmatic choice for small volumes, internal tools, or environments where you already have a mailbox. It is also useful when you need to read historical mail, not just new arrivals.

Low volume and loose latency. If a code can wait a minute, polling every 30–60 seconds is fine.
You control the mailbox. No third-party parser is involved, so you keep full control of the data.
Backfill and reprocessing. You can re-scan old messages if your parser had a bug.
Restricted network. Some environments cannot expose a public endpoint but can make outbound IMAP connections.

The main risks are connection limits, server throttling, and missed messages if your UID tracking is wrong. Always persist the highest processed UID and use UIDVALIDITY to detect mailbox resets.

Practical polling tips

Use UID FETCH with a stored UIDNEXT or last-seen UID rather than SEARCH UNSEEN, which can miss messages marked read by another client.
Keep connections short-lived or use IDLE if the server supports it; long-lived connections can be dropped silently.
Back off on errors and respect server rate limits.
Log the raw message ID and subject so you can debug parsing failures.

When are webhooks the better fit?

Webhooks shine when latency matters — OTP codes, password resets, time-sensitive notifications — or when you do not want to manage an IMAP client at all. The provider handles the mail server, spam filtering, and MIME parsing, and you receive a clean payload.

Near-real-time processing. Codes and confirmations arrive within seconds.
Less protocol code. No IMAP state machine to maintain.
Provider-side parsing. Attachments, HTML and text bodies, and headers are usually normalised.
Scalability. The provider absorbs connection and storage concerns.

The trade-off is that you now depend on an external service and must handle its delivery semantics. That means idempotency, retries, and signature verification.

How do you make webhook handling idempotent?

Webhook providers retry on non-2xx responses or timeouts, and some retry even after a 2xx if their own monitoring is uncertain. Your handler must therefore be safe to call more than once with the same message.

Extract a stable key. Use the provider's message ID if present, otherwise the Message-ID header plus recipient address.
Store it before processing. Insert the key into a unique-constrained table (or a Redis set with a TTL) and return 200 immediately if it already exists.
Process asynchronously. Acknowledge the webhook quickly, then enqueue the work. Long-running handlers cause timeouts and retries.
Make side effects idempotent. Use upserts, conditional updates, or a state machine so a repeated event does not double-send an email or double-credit an account.

This is the same discipline described in our guide to testing signup and verification emails as a developer, where repeated test runs can otherwise create confusing duplicate state.

Retries and dead-letter queues

If your handler fails after the provider's retry window, the message is lost from the webhook stream. Mitigate this with a dead-letter queue: persist the raw payload before processing, and replay failures manually or with a scheduled job. Also monitor your endpoint's error rate — a silent 500 storm is easy to miss.

What breaks in production, and how to prevent it?

Both approaches fail in predictable ways. The table below summarises common failure modes and mitigations.

Failure	Polling	Webhooks	Mitigation
Duplicate processing	Rare with UID tracking	Common on retries	Idempotency key + unique constraint
Missed messages	Wrong UID or mailbox reset	Endpoint down past retry window	Periodic reconciliation scan
Latency spikes	Poll interval too long	Provider queue backlog	Alerting on age of oldest unprocessed message
Auth failures	Expired credentials	Rotated signing secret	Secret rotation with overlap
Parsing errors	Malformed MIME	Unexpected payload shape	Store raw message; version your parser

For any system that receives verification codes, also consider the security model: codes are sensitive and short-lived. Our article on how OTP verification works covers the lifecycle and why you should never log full codes in plain text.

Can you combine polling and webhooks?

Yes, and for critical flows it is often wise. Use webhooks for low-latency delivery and a periodic polling reconciliation job to catch anything the webhook missed. The reconciliation job should scan for messages newer than the last processed timestamp and apply the same idempotency keys, so duplicates are harmless.

This pattern is common in payment systems and is equally applicable to email. It costs little and closes the gap between “usually delivered” and “reliably processed”.

Which approach fits your use case?

Prototyping or internal tooling: polling is usually faster to build.
User-facing OTP or password reset: webhooks, with reconciliation.
High-volume inbound parsing: webhooks, with a queue and dead-letter handling.
Regulated or air-gapped environments: polling may be the only option.
Testing disposable inboxes: a simple API poll is often enough; see disposable email for developers.

Sources

In short

Polling is simple, predictable, and easy to reason about, but it adds latency and requires careful UID tracking. Webhooks are fast and offload parsing, but demand idempotency, retries, and monitoring. For anything user-facing or time-sensitive, start with webhooks and add a reconciliation poll. For prototypes and low-volume tools, polling is perfectly adequate. Whichever you choose, persist raw messages, key your processing on a stable message ID, and alert on the age of the oldest unprocessed message.