Every Cold Email Term, Explained

The percentage of emails that couldn't be delivered. Hard bounces (invalid addresses) permanently damage your reputation. Soft bounces (full mailbox, temporary issues) are less severe. Keep your list bounce rate under 2%.

A database of IP addresses or domains flagged for sending spam. Being listed on a major blacklist (Spamhaus, Barracuda, MXToolbox) can halt all your email deliverability overnight.

A planned series of emails (usually 3-7) sent to a prospect over days or weeks. Each email builds on the last, with different angles, shorter length, and increasing directness. Automated by your sending platform.

A digital signature added to every outgoing email that proves the message wasn't altered in transit and was sent from your domain. It's a cryptographic handshake between your sending server and the recipient's server.

A policy layer on top of SPF and DKIM that tells receiving servers what to do when an email fails authentication — quarantine it, reject it, or do nothing. Also sends you reports on who's sending email using your domain.

The process of gradually increasing email send volume from a new domain to build a positive sending reputation with ISPs. Sending 1,000 emails on day one from a fresh domain is a guaranteed spam trigger. Warming typically takes 4-8 weeks.

Instructions stored in the Domain Name System that control how your domain behaves online. For email, the critical records are SPF (TXT), DKIM (TXT), DMARC (TXT), and MX. All cold email infrastructure requires correct DNS setup.

The time it takes for DNS changes to spread across all global DNS servers. Can take anywhere from minutes to 72 hours. During propagation, some servers see old records while others see new ones.

An IP address used exclusively for your sending. Your reputation is entirely your own — good or bad. Required for high-volume senders (100K+ emails/month). Needs to be warmed from scratch.

The process of checking whether an email address is valid and deliverable before sending. Removes invalid, disposable, and risky addresses from your list. Critical for keeping bounce rates low and protecting your domain reputation.

The overall ability of your emails to reach recipients' inboxes as intended. Affected by domain reputation, IP reputation, email content, list quality, authentication records, and sending behavior. The master metric everything else feeds into.

A free Google tool that shows your domain and IP reputation from Gmail's perspective. Provides data on spam rate, IP reputation, domain reputation, delivery errors, and more. Essential for any serious cold emailer.

Similar to domain warming but for dedicated IP addresses. When you're assigned a fresh IP with no sending history, ISPs treat it with suspicion. Gradually increasing volume builds a trusted reputation on that IP.

The percentage of emails that land in the primary inbox vs. spam, promotions, or other folders. Different from delivery rate — an email can be 'delivered' but still go to spam. Top performers achieve 90%+ inbox placement.

The practice of distributing email sends across multiple mailboxes and domains to avoid hitting daily sending limits and reduce per-domain risk. If one domain gets flagged, the others keep sending while it recovers.

The ongoing practice of cleaning your email list — removing bounces, unsubscribes, inactive addresses, and spam traps. A clean list of 1,000 engaged contacts outperforms a dirty list of 10,000.

A DNS record that specifies which mail server handles incoming email for your domain. Required for receiving email. Points to services like Google Workspace, Microsoft 365, or your hosting provider's mail server.

The percentage of delivered emails that were opened. For cold email, 40-70% open rates are achievable with good deliverability and subject lines. Note: Apple MPP inflates open rates — use reply rate as a more reliable metric.

Dynamic fields in your email template that auto-fill with prospect-specific data — {{first_name}}, {{company}}, {{industry}}. Deep personalization (referencing their recent news, specific pain point) dramatically improves reply rates.

The percentage of emails that received a reply. The most honest metric for cold email success since it can't be gamed by pixel blocking. Strong cold email campaigns achieve 5-15% reply rates.

A DNS record that specifies which mail servers are authorized to send email on behalf of your domain. Without SPF, receiving servers can't verify your email is legitimate, increasing spam folder placement.

A score ISPs assign to your domain and IP based on engagement history — open rates, spam complaints, bounce rates, and unsubscribes. A high reputation means more inbox placement. A low reputation means more spam.

The percentage of recipients who mark your email as spam. Google recommends keeping this under 0.1%. Above 0.3% triggers serious deliverability problems. This is the single most damaging metric to your sending reputation.

Email addresses maintained by ISPs and blacklist operators specifically to catch spammers. They never opted in to anything — if you email them, you're flagged as a spammer. They come from purchased lists and old, unverified data.

The maximum number of emails you should send per domain/inbox per day. Google Workspace recommends 20-50 emails/day from a warmed domain for cold outreach. Exceeding limits triggers spam filters.

A group of IP addresses shared across multiple senders on a platform like Instantly or Smartlead. The platform manages reputation collectively. Easier to get started but one bad sender can affect others.

A series of automated follow-up emails sent to non-responders after the initial email. Most replies come from follow-ups, not the first email. 3-5 step sequences are standard in cold outreach.

Software used to create, schedule, and send cold email sequences at scale. Handles inbox rotation, follow-ups, A/B testing, and deliverability features. The core of any cold email stack.

How long DNS servers cache your record before checking for updates. A low TTL (300 seconds) means changes propagate quickly — useful when setting up new records. High TTL reduces DNS lookup load.

A tool that automatically sends and receives emails between a network of real inboxes to simulate engagement and build domain reputation. Tools like Warmbox and Mailwarm run this 24/7 in the background.