You spent hours crafting your email campaign. The subject line is sharp. The design looks great. The offer is compelling. Then you hit send — and 60% of your messages land in the spam folder.
This is the reality for thousands of email marketers who skip the fundamentals of deliverability. The good news: every item on this checklist is actionable, and fixing even half of them will dramatically improve your inbox placement.
Step 1: Configure SPF, DKIM, and DMARC
These three DNS-based authentication standards are the foundation of modern email deliverability. Without them properly configured, even your most legitimate campaigns can look suspicious to receiving mail servers.
SPF (Sender Policy Framework) tells receiving servers which IP addresses are authorized to send mail on behalf of your domain. DKIM (DomainKeys Identified Mail) attaches a cryptographic signature to each message, allowing the recipient’s server to verify the message hasn’t been tampered with. DMARC ties both together and tells servers what to do when a message fails one of these checks — and gives you reporting visibility into what’s happening with your domain.
Step 2: Audit Your IP and Domain Reputation
Internet service providers and mailbox providers score your sending IP and domain on every campaign you send. A strong reputation means your messages are welcomed. A damaged reputation means they’re filtered or blocked outright.
Use a reputation lookup tool to check your IP and domain status before major sends. Watch for sudden drops in deliverability rates — they often signal a reputation issue that needs immediate attention.
Step 3: Clean Your List
A dirty list is one of the fastest ways to destroy your deliverability. It contains invalid addresses, role-based inboxes like noreply@ or admin@ that were never meant for marketing, and contacts who signed up long ago and haven’t engaged since.
Before every major campaign, scrub your list. Remove hard bounces immediately. Flag soft bounces for monitoring. Set up a re-engagement flow for subscribers who haven’t opened anything in 6+ months — and remove those who don’t respond.
Step 4: Manage Bounces Aggressively
Hard bounces mean the address doesn’t exist. Remove them from your list the moment they occur — never attempt to send to a hard-bounced address again. Soft bounces are temporary delivery failures, but if an address soft bounces repeatedly, treat it like a hard bounce.
Keep your overall bounce rate below 2%. Rates above this threshold are a major red flag for mailbox providers and will suppress your inbox placement.
Step 5: Monitor Your Spam Complaint Rate
When recipients hit “Report Spam,” it registers as a complaint against your sending domain. Gmail and Yahoo have made it clear: complaint rates above 0.1% trigger filtering. Above 0.3%, you’re in serious deliverability trouble.
The single most effective way to reduce complaint rates is making it easy — genuinely easy — to unsubscribe. A visible one-click unsubscribe link in every email protects you more than any content filter optimization ever will.
Step 6: Cultivate Engagement
Mailbox providers don’t just look at the bad signals — they look at the positive ones too. Opens, clicks, replies, and even the act of moving a message from spam to inbox are all engagement signals that boost your sender reputation.
Focus on sending to your most engaged segments first. Build campaigns that earn real interactions. Over time, a highly engaged list becomes a powerful asset that gets preferential inbox placement.
Step 7: Review Your Content for Spam Triggers
Certain words, phrases, and formatting choices consistently raise spam filter scores. Avoid excessive use of words like “free,” “guaranteed,” “act now,” and “limited time offer.” Don’t write in ALL CAPS. And always include a plain-text version of your HTML email.
The goal isn’t to avoid useful content — it’s to present that content in a way that looks like a legitimate, professional message rather than a bulk spam blast.
Step 8: Check Blacklists Before You Send
There are dozens of email blacklists that mailbox providers reference when making delivery decisions. Your sending IP or domain can land on one of these lists after a spike in complaints, a compromised account, or even a configuration error.
Check the major blacklists regularly. If you’re listed, initiate the removal process immediately — most lists have a straightforward delisting procedure as long as you’ve resolved the underlying issue.
Step 9: Keep Your Sending Volume Consistent
Mailbox providers are trained to be suspicious of sudden volume spikes. If your typical send is 5,000 emails per week and you suddenly blast 200,000, that pattern looks like a compromised account or a spam campaign.
Scale gradually. If you’re warming up a new IP address, start small — a few hundred emails per day — and increase volume over several weeks as positive engagement signals accumulate.
Step 10: Segment Your Audience
Not every subscriber on your list wants every email you send. Segmentation — splitting your list by engagement level, purchase history, interests, or geography — ensures each message goes to the people most likely to welcome it.
Segmented campaigns consistently outperform batch-and-blast sends on every metric: open rates, click rates, conversion rates, and most importantly, deliverability. When people want your email, they open it. When they open it, your reputation improves. It’s a virtuous cycle.
Start Sending the Right Way
Deliverability isn’t magic. It’s a discipline. Work through this checklist systematically, and you’ll build the kind of sender reputation that gets your messages into the inbox — every time.
Ready to put these principles into practice? Start Sending with Mailpipe