Time to Inbox (TTI)
Lettermint is fast and we can prove it! Our real-time Time to Inbox metrics track emails across major providers. Because when it comes to password resets and order confirmations, every second counts.
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What is Time to Inbox (TTI)?
Time to Inbox (TTI) measures how long it takes for an email to travel from our servers to the recipient's inbox. We built a system that tracks this across Gmail, Outlook, Yahoo and other providers. It's the real test of email speed - not when we send it, but when it can be viewed in the inbox. Here's how it works.
Send Email
We send test emails to the most popular providers (e.g. Gmail, Yahoo, Outlook) using the same Lettermint API everyone uses. The stopwatch starts now.
Process Email
Our transactional email infrastructure processes the email just like any other. We don't - and can't - prioritize these test emails to ensure fair measurements.
Deliver Email
Our servers deliver the email like an envelope to the provider's inbox.
Provider Validation
The receiving provider runs their checks - spam filters, authentication, security. This is outside our control but we optimize everything to pass quickly.
Inbox Arrival
Email successfully delivered and ready to open. We stop the timer here.
Calculate Time to Inbox
We retrieve the email from the inbox and check when it arrived. Now we know the complete journey time from API call to inbox arrival. That's the Time to Inbox.
Monitoring
We continuously monitor Time to Inbox across all major email providers, 24/7. Every 15 minutes, we send test emails through our regular infrastructure and measure exactly how long they take to reach the inbox. No shortcuts, no priority lanes, no express delivery stickers - just real performance data.
This constant monitoring helps us spot issues before they affect you. If delivery times spike at any provider, we investigate immediately. By tracking these metrics publicly, we hold ourselves accountable to maintaining the fastest possible email delivery for everyone using Lettermint.
Bjarn
Morning' team! I'm on it!
Time Sensitive
Spectate
Lettermint performance threshold
Messages
TTI over 30s threshold
Inbox
Transactional
Broadcast
Dedicated Infrastructure
We keep transactional and broadcast emails completely separated. Why? When someone requests a password reset, it can't get stuck behind thousands of newsletters in a queue. Critical emails need their own fast lane.
By maintaining dedicated servers and IP pools for each type, we ensure your transactional emails always arrive instantly. Newsletter campaigns won't slow down your password resets, and marketing sends won't affect your transactional reputation. It's like having express delivery just for urgent mail.
Frequently Asked Questions
What is Time to Inbox (TTI)?
Time to Inbox measures the complete journey of an email from the moment it's sent through our API until it arrives in the recipient's inbox. It's the real-world speed test that shows how long your customers actually wait to receive their password resets, order confirmations, and other critical emails.
How do you measure Time to Inbox?
We send test emails every 15 minutes to major providers using our standard API and infrastructure. Once sent, we retrieve the email from the inbox and check its headers to see the exact arrival time. The difference between sending and arrival gives us the Time to Inbox.
Which email providers do you monitor?
We continuously monitor Gmail, Yahoo, Outlook, iCloud, AOL, GMX, Zoho. These represent the vast majority of email addresses worldwide, giving you a comprehensive view of delivery performance across different systems.
What affects email delivery speed?
Several factors impact speed: provider processing times, spam filtering, authentication checks, network conditions, and email content. While we optimize everything on our end, each provider has their own validation processes that emails must pass through.
Do you prioritize test emails for better results?
No, our test emails go through the exact same infrastructure as your emails. We don't - and can't - give them special treatment. This ensures our measurements reflect the real performance you and your customers experience.
How can I improve my Time to Inbox?
Maintain good sender reputation, ensure proper authentication (SPF, DKIM, DMARC), keep your content clean and relevant, and use a reliable provider like Lettermint. Avoid spam triggers and maintain consistent sending patterns for best results.
Why do transactional emails need fast Time to Inbox?
Users expect transactional emails instantly. When someone resets their password or completes a purchase, waiting even a few minutes creates anxiety and frustration. Fast delivery builds trust and keeps your users moving forward without interruption.
What happens when Time to Inbox is high?
When we detect elevated Time to Inbox values, our team investigates immediately. High values usually indicate provider-side delays or broader network issues. We work with providers and adjust our routing to restore normal speeds as quickly as possible.
Ready to deliver emails at lightning speed?
Start sending transactional emails that reach inboxes instantly with Lettermint. Our platform delivers password resets, order confirmations, and critical notifications at the speed your users expect.
Start for free