Sender Reputation

​

What is sender reputation?

Sender reputation is a score that email providers (Gmail, Outlook, Yahoo, etc.) assign to your domain and IP addresses based on your email sending behavior. It directly determines whether your emails land in the inbox, the spam folder, or get rejected entirely. Think of it like a credit score for email. A good reputation means email providers trust you. A bad reputation means they don’t.

​

How reputation is calculated

Email providers don’t publish their exact algorithms, but the key factors are well known:

​

Positive signals

​

Negative signals

​

Domain reputation vs IP reputation

There are two layers of reputation: Domain reputation — tied to your domain (e.g., acme.com). This follows you regardless of which service you use to send emails. It’s built over time based on all emails sent from your domain. IP reputation — tied to the IP address of the sending server. When you use SendKit, your emails are sent from shared or dedicated IPs managed by SendKit. Domain reputation is increasingly more important than IP reputation. Gmail, for example, weighs domain reputation heavily in their filtering decisions.

​

Spam traps

Spam traps are email addresses specifically designed to catch senders with poor list hygiene. There are three types: Pristine traps — email addresses that were never used by a real person. They’re created by email providers and anti-spam organizations and seeded across the internet. If you send to one, it means you scraped or purchased your list. Recycled traps — old email addresses that were abandoned by their original owner and repurposed as traps. If you send to one, it means you haven’t cleaned your list in a long time. Typo traps — addresses at common misspellings of popular domains (e.g., gmial.com, yaho.com). They catch senders who don’t validate email addresses at signup.

​

Monitoring your reputation

​

Google Postmaster Tools

Google Postmaster Tools is a free tool that shows how Gmail views your domain. It shows:

• Domain reputation (High, Medium, Low, Bad)
• IP reputation
• Spam rate
• Authentication success rates
• Encryption rates

You need to verify domain ownership to access the data. If you send any volume to Gmail users, this is essential.

​

SendKit metrics

SendKit tracks key deliverability metrics in your dashboard:

• Bounce rate — percentage of emails that bounced
• Complaint rate — percentage of emails marked as spam
• Delivery rate — percentage of emails successfully delivered

Monitor these regularly. Industry thresholds:

​

Building and maintaining reputation

​

For new domains

New domains have no reputation — email providers don’t know whether to trust you. This is why SendKit has an automatic domain warmup period that gradually increases your sending volume over 14 days. During warmup:

1. Send to engaged recipients first — people who have recently signed up or interacted with your product
2. Keep volume low — follow the warmup schedule
3. Monitor metrics closely — watch for bounces and complaints

​

For established domains

1. Clean your list regularly — remove addresses that consistently bounce
2. Honor unsubscribes immediately — never send to someone who opted out
3. Maintain consistent volume — avoid sudden spikes in sending
4. Authenticate properly — ensure SPF, DKIM, and DMARC are all passing
5. Segment your sending — send relevant content to relevant recipients

​

Recovering from a bad reputation

If your reputation has degraded:

1. Stop sending to anyone who hasn’t engaged recently
2. Identify the cause — high bounces? complaints? spam traps?
3. Clean your list aggressively — remove anyone who hasn’t opened in 90+ days
4. Start sending again slowly — treat it like a warmup
5. Only send to confirmed opt-ins — double opt-in if possible

Recovery takes time — typically 2–4 weeks of clean sending behavior.

​

FAQ