Guides

Email deliverability guides

Everything on why emails land in spam — and how to fix it.

• deliverability Does Your Domain TLD Affect Email Deliverability? (.com vs .io, .xyz, .co) Unusual TLDs carry slightly more filtering risk, but far less than people assume. Authentication, domain age and sending history outweigh the extension in every case.
• deliverability Email Deliverability Tools: What Each Category Actually Does Email deliverability tools split into six categories that solve different problems. Here's which category fixes which symptom, so you stop buying the wrong one.
• warmup Best Email Warmup Tools in 2026: Features & Pricing Compared Twelve warmup tools compared on a published, falsifiable framework — including the measurement bug that makes most inbox-rate numbers in this category too high.
• authentication SPF, DKIM and DMARC All Pass — So Why Is My Email Still in Spam? Authentication is a floor, not a ranking factor. Passing it stops you being rejected; it earns you nothing. Here's what decides placement once DNS is clean.
• warmup Does Email Warmup Actually Work? What the Data Shows Warmup skeptics ask a fair question: where's the evidence? Here's what warmup provably does, what it cannot do, and why most reported inbox rates are too high.
• warmup Free Email Warmup Tools: What's Actually Free and What Isn't Most 'free email warmup tools' are trials, bundled features, or free tiers with a one-mailbox cap. Here's what each one really gives you, and what free can't do.
• spam placement Inbox Placement Test: How to Check Where Your Email Actually Lands An inbox placement test tells you which folder or tab your mail reached, not just whether it was accepted. Here's how to run one and why most results are optimistic.
• cold email Instantly and Smartlead Alternatives for Warmup (and When You Don't Need One) Instantly and Smartlead bundle warmup free. Here's the honest case for sticking with it, and the three specific situations where a separate tool earns its cost.
• cold email Do Links in Cold Email Hurt Deliverability? Separating Rule from Folklore The 'never put a link in the first email' rule is mostly folklore. What actually matters is the domain you link to, its reputation, and whether you're using a redirect.
• spam placement Inbox Placement Dropped Suddenly: A Diagnostic Checklist Placement fell overnight and nothing obvious changed. Here's the order to check things in, and why a drop across multiple ESPs at once points somewhere specific.
• cold email Why Cold Email Domains Get Burned (and How to Tell Before It's Too Late) Domains don't die from bad copy. They die from volume ramped too fast, unverified lists, and spam complaints — and the warning signs appear weeks before replies drop.
• deliverability Email Bounce Back: Hard vs Soft Bounces and How to Fix Them What a bounce back message actually means, the difference between hard and soft bounces, how to read the SMTP code inside one, and how to get your bounce rate back under control.
• provider Gmail SMTP Settings: Ports, App Passwords and Sending Limits The correct Gmail and Google Workspace SMTP settings — server, port, encryption — plus app passwords, the errors you will hit, and the sending limits nobody mentions.
• provider Gmail Sending Limits: The Real Numbers and What Happens When You Hit Them Gmail and Google Workspace sending limits explained — daily caps, per-message recipient limits, the hidden throttle on new accounts, and how to send more without getting locked.
• cold email Cold Email Deliverability: How to Avoid the Spam Folder Cold email has the hardest deliverability problem in email marketing — zero prior engagement. Here's the specific checklist that keeps cold outreach out of spam.
• blacklist Email Blacklist Check & How to Get Delisted How to check if your domain or IP is on a spam blacklist, why it happened, and the exact steps to get delisted from Spamhaus, SpamCop, Barracuda, and more.
• spam placement Email Spam Trigger Words: The 2026 List (and How to Avoid Them) A practical list of spam trigger words that send emails to junk — plus what to write instead. Test any email free with our spam-score checker.
• warmup What Is Email Warmup (and When Do You Actually Need It)? Email warmup builds sender reputation by gradually increasing volume with real engagement. Here's when you need it, how it works, and how it fits with content and authentication.
• provider Google Postmaster Tools: The Complete Setup Guide How to set up Google Postmaster Tools and read its reports — domain reputation, spam rate, authentication, and delivery errors — to fix Gmail deliverability.
• spam placement How to Stop Emails Going to Spam: A Step-by-Step Fix A practical, in-order checklist to stop your emails from going to spam — content, authentication, and reputation fixes, with free tools to check each one.
• provider Outlook SMTP Settings: The Complete Setup Guide The correct Outlook and Microsoft 365 SMTP settings — server, port, encryption — plus common connection errors and how to fix them.
• spam placement What Happens When Your Email Lands in the Spam Folder Why the spam folder exists, what triggers it, how to find out if you're being filtered, and what to do once you know.
• spam placement SpamAssassin Score Explained: What It Means and How to Lower It What a SpamAssassin score actually measures, what threshold triggers spam filtering, and how to lower your score — with a free checker for the content rules it weighs most.
• authentication SPF, DKIM & DMARC Explained (with Free Checkers) What SPF, DKIM, and DMARC actually do, how they work together, and how to set each one up correctly — with a free checker to test your domain right now.
• spam placement Why Do My Emails Go to Spam (and How to Fix It) Emails go to spam for three fixable reasons: content, authentication, and sender reputation. Here's how to diagnose which one is hurting you and get back to the inbox.