Email Speed Test

A real-time head-to-head comparison of transactional email delivery speed. Three checkpoints. One winner.

1

API Response

How fast the provider accepts the send request

2

Queue Processing

Time spent in the provider's internal queue

3

Inbox Arrival

Actual delivery to the destination mailbox

How this test works

We fire the same email through two providers simultaneously and measure three checkpoints along the way.

1

API Response

We send identical emails through both Postmark and SendGrid at the same time. This checkpoint measures how quickly each provider's API accepts the request — essentially, how fast the email enters their system.

2

Queue Processing

Once accepted, the email sits in the provider's internal queue until it's actually transmitted to the receiving mail server. We detect this via delivery webhooks — a callback the provider sends once the email has been handed off.

3

Inbox Arrival

The email lands in the destination inbox. We detect this by sending to a controlled mailbox that forwards inbound emails back to our server via webhook, giving us an exact arrival timestamp.

Things to keep in mind

This test measures raw speed under ideal conditions. Real-world email delivery is more nuanced.

Controlled inbox, not real-world delivery

Both emails are delivered to the same test inbox. Real-world delivery to Gmail, Outlook, or Yahoo involves additional processing by those providers — spam filtering, reputation checks, and content scanning — that can add seconds or more.

Speed ≠ deliverability

A fast delivery time doesn't guarantee inbox placement. Emails can be "delivered" but still land in spam. Factors like sender reputation, domain authentication (SPF, DKIM, DMARC), and recipient engagement history all influence where an email ends up.

Webhook timing has variability

The "Queue Processing" checkpoint relies on each provider's delivery webhook, which may fire slightly before or after the email actually reaches the destination server. This can occasionally cause the Inbox Arrival timestamp to appear before Queue Processing.

Single data point, not a benchmark

Network conditions, provider load, and time of day all affect delivery speed. Run the test multiple times for a better picture — no single result tells the full story.