Notes from the deliverability lab.
What is cold email? A 2026 guide for B2B teams new to outbound
Cold email is unsolicited outreach to a prospect you have not contacted before. Legal in most jurisdictions, effective when done right, harmful when done wrong. Start here.
The InboxLee TeamMay 23How to find leads for cold email in 2026: the data-source playbook
Six lead-source categories, the realistic cost per validated record, and the data-quality patterns that separate workable lists from list-burning ones.
The InboxLee TeamMay 23How long should a cold-email follow-up sequence be in 2026?
Three to five sends. Beyond that, marginal reply rate craters and unsubscribe rate climbs. Here is the shape of the curve and why it falls off so fast.
The InboxLee TeamMay 23Email greylisting in 2026: what it is and how it affects cold-email delivery
Greylisting is a 20-year-old spam-prevention trick that some receivers still use. It introduces a 5-30 minute delay on first delivery and shows up in your logs as a soft bounce.
The InboxLee TeamMay 23Mailbox naming conventions for cold email: what looks personable and what looks spammy
Mailbox names are a 0.5-second trust signal. first.last@yourdomain.com wins over team@. Here is the full naming hierarchy.
The InboxLee TeamMay 23Is cold email dead in 2026? An honest answer with data
Cold email is not dead. It is operationally harder than 2019, which makes it more profitable for the teams that do it well. Here is what changed and why.
The InboxLee TeamMay 23SMTP bounce codes explained: 4xx, 5xx, and what each one tells a cold-email operator
Every cold-email bounce returns a numeric SMTP code. Most operators ignore them. Reading the codes turns a black-box bounce into a specific problem you can fix.
The InboxLee TeamMay 23How to segment a cold-email list in 2026 for higher reply rates
Segmentation is the difference between 1 percent and 5 percent reply rates. Three axes that matter, three that do not, and the practical workflow.
The InboxLee TeamMay 23Cold email vs cold calling in 2026: which channel wins for B2B outbound
Different channels, different unit economics, different burn risks. Honest comparison with data on reply rates, cost per meeting, and when each channel wins.
The InboxLee TeamMay 23Cold email templates vs fully custom messages: where each one wins in 2026
Templates scale. Custom messages convert. The real question is where the right cutoff sits. Hint - not where most teams set it.
The InboxLee TeamMay 23