Notes from the deliverability lab.
Gmail vs Outlook cold-email placement: what changes when your recipients use different providers
Workspace and M365 use different spam filters, different reputation systems, and different sender requirements. Here is how cold-email placement diverges between them.
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 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 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 vs marketing email: the operational and legal differences that matter
Both arrive via SMTP, both look like email. The infrastructure, compliance, deliverability rules, and reply expectations are wildly different.
The InboxLee TeamMay 23Should you use tracking pixels in cold email? The honest cost-benefit in 2026
Apple MPP, Gmail prefetching, and modern spam filters have changed the math on email open tracking. Most cold-email teams should turn it off.
The InboxLee TeamMay 23Spamhaus SBL vs DBL: which list is which and what they each block
Spamhaus runs multiple blacklists. The SBL blocks IPs, the DBL blocks domains, and the consequences for cold email are very different.
The InboxLee TeamMay 23Gmail and Yahoo bulk-sender rules in 2026: what cold-email operators actually need to ship
Five required signals, one hard threshold at 5,000 emails per day, and a quiet penalty most senders only notice after the placement chart drops. Pulled from what we apply by default at provisioning.
The InboxLee TeamMay 22The one-click List-Unsubscribe header for cold email: what it is, how to add it, how to verify it
One header. Two lines of metadata. Gmail and Yahoo render a one-tap unsubscribe button at the top of your message. Required above 5,000 sends per day and a quiet positive signal even below.
The InboxLee TeamMay 21What actually caps your cold email reply rate in 2026
Industry "benchmarks" tend to be inflated and self-reported - ours would be too, so we are not publishing one. Here is what actually moves reply rate, and how to tell an infrastructure problem from a copy problem.
The InboxLee TeamMay 19