Glossary
What is cold email?
Cold email is a first email to a person who has not asked to hear from you and has no relationship with you, sent to start a business conversation. It is legal in many places under conditions, such as a clear sender and a working way to opt out.
Published by Sellinger AI. Numbers and settings checked on 19 October 2026 against the fact register. Report an error.
What makes a cold email work?
- A short subject that matches the content.
- One reason you wrote to this person.
- One question, not a pitch deck.
- A real sender and a way to opt out.
How should you warm up a mailbox?
A new mailbox that sends a lot on day one looks like spam. Increase slowly. Example schedule from a doubling rule: 5 a day for 3 days, 10 for the next 3, 20, then 40, then the cap.
| Days | Sends per day |
|---|---|
| 1 to 3 | 5 |
| 4 to 6 | 10 |
| 7 to 9 | 20 |
| 10 to 12 | 40 |
| 13 onwards | 50 |
Common mistakes
Sending from your main domain, skipping the opt out, and buying lists with old addresses. Check bounces after the first batch.
How Sellinger handles it
Every connected account has daily limits that the agent cannot exceed, set per account. LinkedIn defaults are 20 invitations a day and 150 a week. Email defaults to 50 sends a day per mailbox, with an optional warm up that starts at 5 a day and doubles every 3 days up to the limit. Cold email can carry an unsubscribe line and the standard one click unsubscribe headers. It is a setting for each mailbox. Before every send the platform checks the suppression list, and a clear opt out reply stops the agent and closes the lead.
See the email agent, cold email vs LinkedIn outreach and cold outreach.
Common questions
Is cold email legal?
Does Sellinger add an unsubscribe link?
How many cold emails a day is safe?
Sources and method
Sellinger email worker defaults, unsubscribe setting and suppression code, checked 19 October 2026.
Related: Cold outreach, Email agent, Cold email vs LinkedIn, Outreach rules.
