Email deliverability, decoded.
Field notes, benchmarks, and practical guides on getting your email into the inbox, from authentication and reputation to content and the filters that decide it all.
What Changed in Email Deliverability in 2026 DMARC became RFC 9989, Gmail and Outlook.com moved to rejections, business mailboxes got their own rules, and regulators made the open pixel a consent question.
How to Send a Test Email in Klaviyo (and What It Will Not Tell You) The exact click path for a Klaviyo test send, the 30-recipient cap, the monthly quota, everything Preview & test strips out, and when you need a real send. How to Send a Test Email in SendGrid (and Read the Result Right) The click path for a SendGrid test send, why it rewrites your subject line, how Spam Test and Inbox Rendering Test differ, and what Email Testing credits cost. How to Send a Test Email in Mailchimp (and What Each One Costs) The click path for a Mailchimp test email, why every test burns a send credit, the From address the template builder substitutes, and what Inbox Preview costs. How to Send a Test Email in Salesforce Marketing Cloud The Content Builder test send path, the five-address cap, the [Test]: subject qualifier, and why every Marketing Cloud test bills against your send threshold. How to Send a Test Email in HubSpot (and Why It Is Not From You) The click path for a HubSpot test email, why it arrives from noreply@hubspot.com, what that breaks, and which checks need a real Send now instead. How to Send a Test Email in ActiveCampaign (Both Designers) The click path in the Email Designer and the Classic Designer, the 5-address cap, what will not render, and why ActiveCampaign disclaims its own Spam Check. How to Send a Test Email in Brevo (and Why the Links Expire) How to set up a Brevo test list, send a test from Preview & test, the 20-address cap, and why free-plan test links stop working after about 30 minutes. How to Send a Test Email in Constant Contact (and What It Changes) The Preview & Test click path, the five-address cap and 50-per-day limit, the test banner Constant Contact adds, and the footer links it removes. How to Send a Test Email in Amazon SES (and What It Proves) The SES console Send test email path, what the mailbox simulator addresses do, why the sandbox blocks external testing, and what SES charges for real placement. Email Subdomain vs Root Domain: What to Send From Should you send marketing email from a subdomain or your root domain? What a sending subdomain really isolates, what crosses anyway, and when not to migrate. DKIM2 and DMARCbis: What Changes Next in Email Authentication DKIM2 signs a message at every hop so forwarding no longer breaks authentication. Where the IETF draft stands, what DMARCbis changes, and what to do now. Top Email Spam Prevention Techniques for Marketers How to stop marketing emails landing in spam: list permission, subject lines, content testing, SPF, DKIM, DMARC, one-click unsubscribe and CAN-SPAM.
