Email Deliverability

Definition Email deliverability is the measure of whether a message successfully lands in the recipient's primary inbox, rather than being filtered into the spam folder, promotions tab, or quarantined by the receiving server.

Delivery vs. Deliverability These two terms are often confused.

• Delivery simply means the receiving server accepted the email without bouncing it. If an email goes straight to the spam folder, it is still counted as "delivered."
• Deliverability (or inbox placement) is about where the email lands after it is delivered.

How Inbox Placement Actually Works Mailbox providers like Google and Microsoft do not publish their exact spam algorithms, but deliverability is generally determined by three factors:

1. Authentication: Proving you are who you say you are. This requires properly configured SPF, DKIM, and DMARC records. Without these, modern mailbox providers will often reject or quarantine your mail by default.
2. Reputation: Both your domain reputation and your IP reputation. If users frequently mark your emails as spam, or if you consistently send emails to invalid addresses (high bounce rate), your reputation drops.
3. Engagement: The feedback loop. If recipients open, reply to, or forward your emails, providers learn that your mail is wanted. Conversely, if thousands of emails are ignored or deleted without being opened, it signals low relevance.

Diagnosing Deliverability Issues If your open rates suddenly drop, you have a deliverability problem. The first step is isolating the cause:

• Check your domain on blacklists (e.g., Spamhaus).
• Verify that your DNS records (SPF/DKIM/DMARC) haven't been altered.
• Review your bounce rates. A bounce rate above 2-3% usually indicates poor list hygiene and will quickly degrade sender reputation.

Best Practices for Outbound Because reputation is tied to the domain, most outbound sales teams use secondary domains (e.g., @getcompany.com instead of @company.com). This isolates the risk of outbound campaigns from the company’s primary communication channels. Senders also typically limit daily volume per inbox to mimic normal human behavior and manage reputation risk.