Deliverability is your emails' ability to land in your recipients' inbox, rather than the spam folder or a rejection. An email can be "sent" without ever being "received" where it's actually read. Deliverability measures that gap and, in practice, decides whether your message has any chance of being read.
Why deliverability is decisive
You can write the best message in the world: if it lands in spam, nobody sees it. It's the first filter, before the content even matters. Good deliverability underpins everything else in your email prospecting.
Mail providers like Gmail and Outlook are constantly sorting. They aim to protect their users from unwanted mail and rely on signals to decide where each message lands. Understanding these signals keeps you from unknowingly sabotaging your own campaigns.
The factors that affect deliverability
Several elements determine where your email ends up:
- Sending reputation, built up over time by your domain and address. A clean history builds trust with mail providers.
- Technical authentication, notably SPF and DKIM, which proves your emails really come from your domain and haven't been spoofed.
- The domain you use: a domain dedicated to prospecting protects your main domain in case of trouble.
- Recipient behavior: opens and replies help, spam reports hurt significantly.
- Sending pace: a gradual ramp-up beats one massive burst.
None of these best practices guarantees a specific outcome. They reduce risk and tilt the odds in your favor, which is what actually matters.
Kaptor and your sends
Sending from your own inbox, with an authenticated address and a reasonable volume, already puts you on solid footing. Kaptor lets you write from your Gmail, Workspace, or a dedicated domain, and track replies in the same place.
Content matters just as much as the technical side. A cold email that's relevant, targeted, and easy for the recipient to act on protects your sending reputation. For the full method and the framework to follow, check out our page on compliant cold email.