Blog
Cold email, explained properly.
Deliverability, provider limits and honest analytics, written by people who build a sending engine for a living.
Deliverability · 7 min
Gmail sending limits in 2026: what Google allows, and what's safe for cold email
Google's daily limits for Gmail and Workspace, the errors you'll see when you hit them, and the much lower numbers that keep a cold email mailbox healthy.
ReadAnalytics · 6 min
Why your cold email open rates are wrong
Apple Mail Privacy Protection, security scanners and link checkers open emails nobody reads. Here's how to spot machine opens and what to measure instead.
ReadOutlook · 6 min
Fixing "SmtpClientAuthentication is disabled for the Mailbox" in Outlook
What Microsoft's 535 5.7.139 error means, why SMTP sign-in keeps getting switched off, and the fixes that work for Outlook.com and Microsoft 365 mailboxes.
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