All resources
Glossary
Cold email & deliverability glossary
Plain-language definitions for the terms that come up most in cold outreach and deliverability.
- Bounce rate
- The share of sent emails a mail server refuses to deliver. A hard bounce means the mailbox doesn’t exist; a soft bounce means it’s temporarily unreachable. See what a high bounce rate costs you.
- Catch-all domain
- A domain configured to accept mail to any address at all, valid or not — so no verification method can confirm a specific mailbox exists there. Detected, not guessed around.
- Cold email
- An email sent to someone with no prior relationship or opt-in, typically for sales or business development. Distinct from a newsletter or a reply to an inbound inquiry.
- Deliverability
- Whether your email reaches the inbox at all, as opposed to spam or nowhere. Determined by domain authentication (SPF/DKIM/DMARC), sender reputation, and content — not by whether the address exists.
- DKIM
- DomainKeys Identified Mail — a DNS record and cryptographic signature that proves an email wasn’t altered in transit and actually came from your server. See SPF, DKIM and DMARC explained.
- DMARC
- Domain-based Message Authentication — a DNS record telling receivers what to do when SPF or DKIM fails (allow, quarantine, or reject), and where to send reports about who's sending mail as your domain.
- Domain warmup
- Gradually increasing send volume on a new or dormant domain so mailbox providers build trust in it, rather than throttling or spam-folding it by default. See warming up a new sending domain.
- Email finder
- A tool that predicts a person's work email from their name and company domain, using common naming conventions (first.last@, flast@, and so on).
- Email pattern
- The naming convention a company uses for work emails — first.last@, first@, flast@ — usually consistent across everyone at that domain once you know it.
- Email verification
- Confirming a specific mailbox exists by checking with the receiving mail server, as opposed to only checking the address is well-formed or the domain accepts mail. See how to verify a work email.
- MX record
- A DNS entry naming the mail server responsible for a domain. Having one just means the domain can receive mail somewhere — it says nothing about any specific address.
- Sender reputation
- A mailbox provider's ongoing assessment of a sending domain, built from bounce rate, spam complaints, and engagement over time. Low reputation means spam-folding by default, regardless of content.
- Spam trap
- An email address, often previously real but now abandoned, used specifically to catch senders with poor list hygiene. Hitting one signals to providers that your list wasn't properly maintained.
- SPF
- Sender Policy Framework — a DNS record listing which servers are authorized to send mail for your domain. See SPF, DKIM and DMARC explained.
Ready to try it on a real list?
A few free lookups a day, no card. If it comes back verified, it’s genuinely verified.
Get started