Notes from the deliverability lab.
Best cold email infrastructure platforms in 2026: 10 providers compared
Honest, hands-on ranking of the 10 cold email infrastructure platforms that actually ship mailboxes at agency scale. Pricing, partner status, DNS automation, dedicated IPs, and what each is best for.
The InboxLee TeamMay 30, 2026 · 14 min readAre pre-warmed mailboxes worth it? An honest cost-vs-time breakdown
Pre-warmed mailboxes cost $5/mo vs $2.50 for standard, and they let you send cold on day one instead of waiting 14 days. Here is exactly when the premium pays off, and when it does not.
The InboxLee TeamJul 4BIMI for cold email: what it is, who can use it, and whether it actually helps placement
A logo next to your name in Gmail and Yahoo. Looks great in B2C marketing. Worth almost nothing for cold outbound until you cross specific thresholds.
The InboxLee TeamMay 23Why your cold email lands in Gmail Promotions (and what actually moves it to Primary)
Promotions is not spam. It is also not where most B2B cold email gets answered. Six signals Gmail uses to decide, and which ones you can move.
The InboxLee TeamMay 23Reading DMARC aggregate reports: what they tell you and which ones to ignore
DMARC reports look like XML dumps. They are actually one of the highest-signal deliverability data sources you have access to. Here is what to read first.
The InboxLee TeamMay 23How to recover cold-email sender reputation after a deliverability drop
Reputation recovery is slow, measurable, and reversible. A 30-day playbook for taking a flagged domain back to Primary inbox.
The InboxLee TeamMay 23When is the best time to send cold email in 2026? Data from 750K sends
Most "best time to send" advice is recycled B2C marketing wisdom. Here is what cold-email reply data actually shows for B2B outbound.
The InboxLee TeamMay 23Subdomain vs root domain for cold email: which one protects your main brand
Sending cold from mail.yourcompany.com instead of yourcompany.com is a real strategic call. Here is when each one wins.
The InboxLee TeamMay 23How to get a cold-email domain delisted from a blacklist: the 14-day playbook
Listings on Spamhaus, SURBL, Barracuda, and the other 11 blacklists that matter. Each one has a delisting path. Some take hours; some take 14 days.
The InboxLee TeamMay 23What is a good cold email open rate in 2026? Honest data from 750K sends
Open rates have been compromised by Apple Mail Privacy Protection. Here is what the number actually means in 2026 and the benchmarks that survived the pixel-prefetch era.
The InboxLee TeamMay 23