Email intelligence

Email Deliverability

The ability of an email to successfully reach the recipient's inbox without being blocked or filtered as spam.

Tomba Team
March 23, 2026

Email deliverability measures how effectively your emails land in recipients' inboxes rather than being diverted to spam folders, bounced, or blocked entirely. For B2B sales and marketing teams, high deliverability is non-negotiable because even the most compelling outreach is worthless if it never reaches its intended audience.

Several factors influence deliverability, including sender reputation, email authentication protocols (SPF, DKIM, DMARC), content quality, and list hygiene. Internet service providers and email clients use sophisticated algorithms to evaluate incoming messages, and a poor track record in any of these areas can result in emails being filtered or rejected.

Beyond technical setup, deliverability depends on sending behavior. Sudden spikes in email volume, high bounce rates, and frequent spam complaints all signal to email providers that something is wrong. A gradual warm-up process and consistent sending patterns help establish trust with inbox providers and maintain strong deliverability over time.

Key Points

  • Determines whether your emails reach the inbox or get filtered to spam
  • Affected by sender reputation, authentication, content, and list quality
  • Directly impacts the success of any email-based outreach campaign

How It Works

When you send an email, the receiving mail server checks your domain reputation, authentication records, and sending patterns. Based on these signals, the server decides whether to deliver the email to the inbox, route it to spam, or reject it outright. Consistent good practices build a positive sending history over time.

Best Practices

  • Implement SPF, DKIM, and DMARC authentication on your sending domain
  • Monitor bounce rates and remove invalid addresses from your lists immediately

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