Cold email glossary.
The words you'll meet in cold email, explained in one or two plain sentences.
- Bounce
- An email that couldn't be delivered. A hard bounce means the address doesn't exist; a soft bounce is temporary, like a full mailbox. Keep bounces under 2%.
- Bounce rate
- The share of your emails that bounced. High bounce rates tell providers your list is poor.
- Cold email
- A one-to-one business email to someone you haven't emailed before, with a clear, relevant reason to contact them.
- DKIM
- A digital signature on every email that proves it came from your domain and wasn't changed. Learn more
- DMARC
- A DNS record that tells inboxes what to do when SPF or DKIM fails, and sends you reports. Required by Google and Yahoo for bulk senders. Learn more
- Email sequence
- A series of emails sent to the same person a few days apart, stopping when they reply.
- ESP
- Email service provider: who hosts an inbox, such as Google Workspace, Microsoft 365, Zoho or Yahoo.
- ESP matching
- Sending to each lead from a mailbox on the same provider, for example Gmail leads from your Google mailbox. Learn more
- ESP sending
- Choosing which providers a campaign emails, for example only Microsoft leads. Learn more
- Inbox placement
- Whether your email lands in the inbox, the spam folder or a promotions tab.
- MCP
- Model Context Protocol: a standard way for AI assistants like Claude to use tools, such as launching a campaign. Learn more
- Machine open
- An 'open' caused by software, such as Apple Mail pre-loading images or a security scanner checking links. Not a sign of interest. Learn more
- Personalisation variable
- A placeholder like {{first_name}} that's replaced with each lead's details.
- Role address
- A shared team address like info@ or sales@. Low reply rates and more spam reports.
- Slow start
- Sending few emails from a new mailbox at first, and raising the volume over a few weeks. Learn more
- Smart scheduling
- Spreading each mailbox's daily emails across the working day with random gaps, instead of sending in bursts. Learn more
- Spam complaint rate
- The share of recipients who mark your email as spam. Keep it under 0.1%; Google's limit is 0.3%.
- SPF
- A DNS record listing the servers allowed to send email for your domain. Learn more
- Spintax
- Alternative wordings like {Hi|Hey|Hello}, so each lead gets a slightly different email.
- Throwaway inbox
- A temporary address from a disposable email service. Nobody reads it.
- Warm-up
- Using a network of mailboxes that email each other and fake engagement to build reputation. Now risky: see why we don't do it. Learn more
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