Preflight checks for your email campaign

Every sending service — ESP, CRM, helpdesk, billing system — must be in your SPF record or its mail fails authentication. And SPF is capped at 10 DNS lookups: too many includes silently breaks the whole record.

DKIM is the one mechanism that reliably survives forwarding, and the one the big inbox providers weight most heavily. Missing or weak signatures are a fast track to the spam folder.

Even at p=none, DMARC reports tell you who is sending as your domain and whether their mail aligns. A record nobody monitors is a smoke alarm with no battery.

DMARC only passes when the visible From domain matches the domain your SPF or DKIM authenticated. Sending marketing from a subdomain keeps any reputation damage away from your corporate mail.

Legally required (GDPR, CAN-SPAM and equivalents), and a broken or buried unsubscribe converts annoyed recipients into spam complaints — the single worst signal you can send a mailbox provider.

Gmail and Yahoo require working one-click unsubscribe headers for bulk senders. It also gives unhappy subscribers an exit that doesn't involve the spam button.

Bounce rate and complaint rate are the two metrics mailbox providers weigh hardest. Sending to addresses that haven't opened anything in two years is a slow bleed on your reputation.

Consent protects you legally and reputationally. Purchased or scraped lists are the single fastest route to the spam folder, and the hardest problem to walk back.

URL shortener domains carry their own spam reputation, which yours inherits. Broken links and mixed http URLs are classic filter triggers and a terrible first click for a real customer.

A quiet account suddenly sending 50,000 emails looks like a compromised mailbox to a filter. New or rested infrastructure needs gradual warm-up; established senders need steady rhythms.