Guide
The cold email deliverability checklist
Most cold email problems are deliverability problems in disguise. If your emails land in spam, nothing else matters. Here is the checklist we use before any campaign goes out.
1. Use separate sending domains
Never send cold email from your main company domain. Register one or more similar domains, point their websites at your main site, and send from those. If a sending domain gets into trouble, your main domain and your team's everyday email are untouched.
2. Authenticate every domain
Inbox providers expect three DNS records on every sending domain:
- SPF: lists the servers allowed to send for the domain
- DKIM: signs each email so it cannot be altered in transit
- DMARC: tells providers what to do when SPF or DKIM fail, and where to send reports
3. Warm up new mailboxes
A brand-new mailbox that suddenly sends hundreds of emails looks like a spammer. Start with a handful of emails a day and increase over two to three weeks, while warmup traffic builds a normal pattern of opens and replies.
4. Keep daily limits low per mailbox
Spread volume across several mailboxes instead of pushing one hard. Around 30 to 50 cold emails per mailbox per day is a sensible ceiling for most setups. Send inside business hours in the recipient's time zone.
5. Send plain text
Tracking pixels, wrapped links, images and heavy HTML all add risk. A short plain-text email with no tracking looks like what it should be: one person writing to another.
6. Verify every address
Bounces are one of the fastest ways to damage a domain. Verify every email before sending, treat catch-all domains with care and remove anything you cannot confirm.
7. Write fewer, better emails
Filters learn from how people react. Identical templates sent to thousands of people get ignored, deleted and reported. Emails that are relevant to the reader get replies, which is the strongest positive signal there is.
8. Test inbox placement
Before a campaign goes wide, send to a set of test inboxes across Gmail and Outlook and check where the email lands. Fix anything that lands in spam before you scale.
Questions
How many cold emails can I send per day?
Per mailbox, around 30 to 50 a day after warmup is a safe range for most setups. Add more mailboxes and domains to send more, rather than pushing one mailbox harder.
Do open tracking pixels hurt deliverability?
They can. Tracking pixels and wrapped links are common in bulk mail, and some filters treat them as a negative signal. Many cold emailers now turn them off.
How long does warmup take?
Plan for two to three weeks before a new mailbox reaches full volume.