How to Maintain a Good Sender Reputation

Your sender reputation is a score that Internet Service Providers (ISPs) and inbox providers assign to your domain and IP address based on your sending behavior. A good sender reputation means your emails land in the inbox. A poor one means they go to spam — or get blocked entirely.

Why Sender Reputation Matters

Every time you send an email, inbox providers evaluate signals like your open rates, bounce rates, spam complaint rates, and list quality to decide where to place your message. Building and maintaining a strong reputation takes consistent effort.

1. Only Send to Contacts Who Opted In

Always get explicit permission before sending marketing emails. Contacts who did not opt in are more likely to mark your emails as spam, which directly harms your reputation. Use double opt-in on your sign-up forms to confirm that each subscriber genuinely wants to hear from you.

2. Keep Your List Clean

• Mailzzy takes care of hard bounces by automatically removing invalid email addresses from your sending list.

• Unsubscribe or suppress contacts who have not engaged in the past 3 to 6 months

• Never add purchased, scraped, or rented email addresses to your list

3. Send Consistently

Sending on a predictable schedule helps inbox providers build trust with your domain. Sudden spikes in volume — especially from a new or inactive domain — trigger spam filters.

• Send at least two emails per week to keep your domain active and warm

• Avoid sending nothing for weeks and then suddenly sending to your full list

• If you need to ramp up your volume, follow the warm-up schedule in Mailzzy

4. Write Relevant, Engaging Content

High open rates and click rates signal to inbox providers that your subscribers value your emails. Focus on:

• Clear and honest subject lines that match the email content

• Content that is relevant to the audience you are sending to

• A clear call to action that gives subscribers a reason to engage

5. Make It Easy to Unsubscribe

It may seem counterintuitive, but making unsubscribing easy actually protects your reputation. If a recipient cannot find the unsubscribe link, they will mark your email as spam instead — which is far worse.

Mailzzy includes a mandatory unsubscribe link in every campaign. Never try to hide or remove it.

6. Monitor Your Campaign Metrics

Keep an eye on your campaign reports after every send. Watch for:

• Bounce rate – Should stay below 2%

• Spam complaint rate – Should stay below 0.1%

• Unsubscribe rate – High rates may signal irrelevant content or too-frequent sending

7. Authenticate Your Domain

Domain authentication — SPF, DKIM, and DMARC — is essential for inbox placement. Unauthenticated emails are far more likely to be filtered or rejected. Refer to the Domain Authentication Guide for Mailzzy to complete your setup.