The deliverability fix library
20 step-by-step guides covering every common reason emails land in spam. All free. Plain English.
How to fix DMARC policy set to "monitor only" (p=none)
Your DMARC record is published but set to p=none. Here's why it's a security risk and exactly how to upgrade to p=quarantine safely.
You have no DMARC record. Here's how to publish one.
Gmail and Yahoo now require DMARC for bulk senders. Without it, your cold email is going to spam. 5-minute fix.
Why Gmail says your DKIM isn't aligned (Google Workspace fix)
If your DKIM domain is "gappssmtp.com" instead of your real domain, DMARC fails silently. Here's the 2-minute Google Workspace fix.
No DKIM key found on your domain — how to add one
DKIM is one of three pillars of email authentication. Without it, your cold emails land in spam. Setup guide for Google, Microsoft, SendGrid, more.
SPF too many DNS lookups — how to flatten your record
SPF has a hard limit of 10 DNS lookups (RFC 7208). If you exceed it, your SPF silently fails — every receiver rejects your mail. Fix it in 10 minutes.
No SPF record published — quick fix for any DNS provider
SPF is the first line of email defence. Without one, anyone can spoof your domain. Setup guide for Cloudflare, GoDaddy, Route53, etc.
SPF set to ~all (soft fail) — should you change it?
Soft-fail SPF tells receivers "this might be fake, but deliver anyway." Here's when to harden to -all and when to leave it.
My IP is listed on Spamhaus — how to get delisted
Spamhaus is the most influential blocklist on the planet. If you're on it, your mail is blocked everywhere. Here's how to investigate and request removal.
Removed from email blacklists: complete checklist for 15+ RBLs
Different RBLs (Spamhaus, Barracuda, SORBS, etc.) have different delisting procedures. Here's the full removal guide for each.
Shared IP vs dedicated IP for cold email — which to choose
Should you use a shared IP from your sending provider or pay extra for a dedicated one? The answer depends on volume.
How to warm up a new email sending domain (without burning it)
A brand-new domain has zero sender reputation. Send too much too fast and you'll trigger every spam filter. Here's the 30-day playbook.
Why your cold email lands in Gmail Promotions (not spam, but bad)
Promotions tab = nobody sees your email. Here's the 7 things that get you classified as Promotions and how to fix each.
Cold email open rates below 30%? Here's what to check
Open rates < 30% on cold email = a problem. Could be subject lines, sender reputation, or hidden deliverability issues. Diagnostic checklist.
Find out exactly who's sending email pretending to be your domain
DMARC aggregate reports reveal every IP sending mail as your domain — including the ones you didn't authorize. Here's how to read them.
Apple Mail keeps marking my emails as spam
Apple Mail uses its own filtering separate from Gmail/Outlook. Here's what's different and how to land in the inbox.
Outlook keeps putting my emails in Junk
Microsoft 365 uses Smart Filter + SmartScreen — very different from Gmail. Here's the Outlook-specific fix list.
MXToolbox alternative for SMB teams (faster, cleaner, fairer pricing)
MXToolbox is the standard but expensive and enterprise-flavored. Here's how Conductor compares for smaller teams.
Gmail's 2024 bulk sender requirements — am I compliant?
Gmail and Yahoo enforce strict sender requirements for anyone sending > 5000 emails/day. Here's the checklist.
How to add the List-Unsubscribe header (Gmail one-click compliance)
Gmail requires one-click unsubscribe for bulk senders. The List-Unsubscribe header is how you provide it.
The complete cold email deliverability checklist (2026 edition)
A step-by-step audit covering every signal that matters for cold outbound deliverability today.