How to Avoid the Spam Folder: A Practical Checklist

Authentication (do this first, always)

This is table stakes. Mailbox providers increasingly reject or foldering unauthenticated mail outright.

• SPF: publish a DNS record listing which servers are allowed to send on your domain’s behalf.
• DKIM: sign outgoing mail cryptographically so receivers can verify it wasn’t altered in transit.
• DMARC: tell receivers what to do with mail that fails SPF/DKIM, and get visibility via aggregate reports.
• MailCraft generates the DKIM and DMARC records when you add a domain and checks when they’re live — look in your dashboard for anything still showing "pending."

Warm up before you scale

A brand-new domain or IP sending 50,000 emails on day one looks exactly like an attack to a mailbox provider's spam filter, even if every recipient opted in. Ramp volume gradually — see our dedicated guide on domain warm-up for a week-by-week plan.

List hygiene

Sending to addresses that bounce, complain, or simply never engage is the single most common self-inflicted deliverability problem.

• Remove hard bounces immediately and permanently — don’t retry them.
• Suppress anyone who complains (marks as spam) instantly; never let a suppressed address back onto a list.
• Validate addresses at signup to catch typos and disposable domains before they ever enter your list.
• Periodically re-engage or remove contacts who haven’t opened anything in 90+ days — a smaller, engaged list outperforms a larger, stale one on every metric that matters.

Content signals

Spam filters are less about magic keyword blacklists than they used to be, but a few patterns still hurt: an extreme image-to-text ratio, misleading subject lines relative to content, missing plain-text alternative, and no visible unsubscribe link or a broken one. Keep a working List-Unsubscribe header on every marketing send — it’s both good practice and increasingly a hard requirement from major mailbox providers.

Watch the signals that predict trouble

Complaint rate above roughly 0.1% and bounce rate above roughly 2% are the thresholds where major providers start throttling or foldering your mail. MailCraft’s reputation view tracks both across the last seven days — treat a spike in either as a stop-and-fix signal before you send the next campaign, not something to review at month end.