Improve email deliverability to reach more inboxes

FAQs

• What’s the difference between delivery and deliverability?

  Delivery means your email arrives somewhere (anywhere) in the recipient's mailbox—inbox, spam, or promotions. Deliverability means it reaches the primary inbox where it's most likely to be seen and opened. While delivery is about emails getting to servers, deliverability is about reaching the right destination within those servers.

• What affects your email deliverability?

  Sender reputation ESPs assign reputation scores based on engagement rates, spam complaints, bounce rates, and sending consistency. Strong reputation means better inbox placement. Poor reputation leads to spam filtering or blocking.

  Authentication SPF, DKIM, and DMARC records prove your emails are legitimate. Without authentication, inbox providers can't verify you're who you claim to be, leading to spam filtering or rejection.

  List Quality & Permissions Clean lists with verifiable consent perform dramatically better. Purchased lists, stale addresses, and contacts without explicit permission damage deliverability through high bounces and spam complaints.

  Engagement Rates Opens, clicks, and replies signal that subscribers want your emails. Consistently low engagement tells inbox providers your emails aren't valued, leading to spam folder placement.

  Content Quality Spammy language, excessive links, image-only emails, and misleading subject lines trigger spam filters. Well-designed, valuable content with balanced text-to-image ratios performs better.

  Sending Consistency Regular, predictable sending patterns build trust with inbox providers. Sudden volume spikes, long gaps between sends, or erratic frequency can trigger spam filters.

• Why do my emails go to spam instead of the inbox?

  Common causes include: lack of authentication (no SPF/DKIM setup), poor sender reputation from low engagement or spam complaints, sending to contacts without permission, spammy content or subject lines, sudden volume spikes, or high bounce rates. Inbox providers use sophisticated algorithms that consider dozens of factors when deciding placement.

• What is a warm-up period and do I need one?

  A warm-up period is gradually increasing email volume when starting with a new sending domain, IP address, or after a long break. Begin with small batches to engaged subscribers, then slowly scale up over 2-4 weeks. This builds positive reputation with inbox providers without triggering spam filters. If you're new to Mailchimp or using a new domain, warm-up is essential for strong deliverability.

• Where are bounce rates and why do they matter?

  Bounces occur when emails can't be delivered. Hard bounces (permanent failures like non-existent addresses) and soft bounces (temporary issues like full inboxes) both affect sender reputation. High bounce rates signal poor list management to inbox providers. Mailchimp automatically removes hard bounces from your list. Use double opt-in and regular list cleaning to keep bounce rates low.

• Do I need to set up email authentication?

  Yes. Email authentication (SPF and DKIM) is now required by Gmail and Yahoo for bulk senders and is a best practice for all email marketers. Authentication proves your emails are legitimate and significantly improves deliverability. Without it, inbox providers can't verify you're who you claim to be, leading to spam filtering or rejection. Mailchimp makes authentication setup straightforward with guided instructions.

• What is sender reputation and how do I improve it?

  Sender reputation is a score inbox providers assign based on your sending behavior. Factors include engagement rates (opens, clicks), spam complaint rates, bounce rates, authentication status, and sending consistency. Improve it by: maintaining clean lists, only emailing people with permission, creating valuable content, sending regularly, authenticating your domain, and monitoring performance metrics.

• How often should I clean my email list?

  Clean your list quarterly at minimum, or more frequently if you have rapid list growth. Remove hard-bounced addresses immediately (Mailchimp does this automatically), regularly remove unengaged subscribers who haven't opened emails in 6+ months, use re-engagement campaigns before removal, and implement double opt-in to prevent invalid addresses from joining. Clean lists have dramatically better deliverability.

• Should I use a dedicated IP address for sending emails?

  Most senders achieve better deliverability with Mailchimp's shared IPs—they're established, highly reputable, and managed by our delivery experts. Dedicated IPs make sense for high-volume senders (100k+ emails per week) who want full control over their reputation. However, dedicated IPs require consistent sending volume and careful management. For most businesses, shared IPs provide superior results.

• Does an ESP's infrastructure matter?

  Infrastructure matters tremendously. Reliability, uptime, and transparency all impact deliverability. Mailchimp maintains a public status page with real-time monitoring data, and we take uptime very seriously.

  With 20+ years in business, we've built thousands of servers, our own fiber loops, and identified patterns that enable reliable scaling. This infrastructure can't be quickly replicated—it's the result of decades of investment and expertise.

• What sets Mailchimp’s infrastructure apart from other ESPs?

  Unlike competitors who use third-party vendors, we buy our own servers, use open-source software, and keep expertise in-house. This helps us move faster and iterate quickly.

  We’re built like Facebook or Google – with small infrastructure units and no single points of failure. Everything is distributed. If we need to scale or react, we simply order more servers without going through external vendors.

• How is Mailchimp’s approach to delivery unique?

  Mailchimp’s deliverability team is a technical, data-driven operation that works directly with major mailbox providers, continuously monitors spam tactics, and enforces thousands of provider-specific rules around IP limits, connection rates, message volumes, and core authentication standards like SPF, DKIM, and reverse DNS.

  Mailchimp stays ahead of mailbox provider changes. In February 2024, when Google introduced new Gmail sender guidelines, Mailchimp was already positioned to support domain-level authentication, enabling providers to evaluate individual sender quality rather than just platform reputation.

• How does Mailchimp’s deliverability compare to other ESPs?

  As one of the largest ESPs, we've built strong relationships with block list operators. They respect our commitment to reputation management and work with us when issues arise because they trust our enforcement.

  We're far stricter than competitors about what we allow: no affiliate marketing, no adult content, and very strict permission requirements. We've turned down huge companies to maintain clean reputation. This protects all our users' deliverability—we value platform integrity over short-term revenue.

• What’s Mailchimp’s Omnivore program?

  Omnivore is our automated abuse-prevention system that analyzes accounts and campaigns for risky patterns like high bounce or complaint rates. Omnivore flags and pause potential harmful activity, keeping scammers off and providing a reliable experience for all users.