Guides
Guides
deliverability
Deliverability is the work you don't see until it breaks. When it's healthy, the program runs. When it's degraded, nothing else matters — the best subject line in the world doesn't rescue a reputation at 'Low' on Gmail. These guides cover the plumbing that determines whether lifecycle marketing actually reaches a human.
Most deliverability failures are quiet. The complaint rate creeps from 0.15% to 0.22% over four weeks while the team is focused on launching a new flow. By the time someone notices, Gmail has downgraded the domain and recovery takes 6–12 weeks. The fix is structural: preventive policy, weekly monitoring, and the muscle memory to act early rather than react late.
The guides in this category cover every layer of the deliverability stack. Authentication (SPF, DKIM, DMARC, BIMI) — the cryptographic proof that mail is from who it says. Domain and IP reputation — the two parallel reputation systems and which one actually matters in 2026. List hygiene — the six-rule automatic policy that prevents the reputation damage that requires the recovery playbook. Spam complaints and bounce management — the specific thresholds that trip reputation penalties.
They also cover the tools that tell you where you stand. Google Postmaster Tools. Seed-list inbox placement testing and its limits. Apple Mail Privacy Protection and what it does to your open-rate metrics. When to dedicate an IP vs stay on a shared pool. How to set up subdomains for reputation isolation. The Gmail Promotions tab and whether landing there is actually a problem.
Read these when deliverability is healthy, not when it's broken. The cheapest deliverability incident is the one that never happens — and the policy you set up today is what prevents it.
Deliverability is the cumulative result of every send decision over the lifetime of a domain. This guide covers the four pillars — authentication, reputation, engagement, and list hygiene — and how to recover when one breaks.
12 min read
A dedicated IP has no sending reputation on day one. This guide shows how to ramp to full volume in 14–30 days without triggering spam filters — including the Random Bucket Number methodology most teams miss.
11 min read
Gmail truncates any email larger than 102KB and hides the rest behind a 'View entire message' link that almost nobody clicks. This guide shows what counts toward the limit, the six real sources of bloat, and how to consistently stay under it.
8 min read
In 2021, Apple broke the email open rate. Four years later, the dust has settled — and the lifecycle programs that adapted are outperforming the ones still measuring like it's 2020. Here's what actually changed.
8 min read
The page every lifecycle team ignores is the one that quietly decides sender reputation, suppressed-list quality, and the fate of your next quarter's deliverability. A short defence of why it's worth the ten-minute rebuild.
7 min read
Three DNS records decide whether your marketing email is trusted or binned. Gmail and Yahoo have required all three for bulk senders since 2024. This is the practitioner's explainer — what each one does, how they interact, and the configuration that actually works.
10 min read
Every Braze sales conversation pitches the dedicated IP. Most programs don't need one. Here's the volume threshold that actually justifies a dedicated IP, the risks most teams don't anticipate, and when the shared pool is genuinely the better call.
8 min read
List hygiene isn't cleanup; it's a continuous policy that runs automatically. Here's the six-rule policy every lifecycle program should have written down, each tied to a specific deliverability outcome.
8 min read
Bounce rate is the simplest deliverability metric to read and the easiest to get wrong. Here's what each bounce type actually means, the thresholds that trigger real problems, and the fix order when your bounce rate starts climbing.
8 min read
Spam complaints are the strongest negative reputation signal in email. They compound faster than bounces and recover slower. Here's the playbook — what triggers them, how to detect them early, and the four levers that reliably bring the rate down.
9 min read
Deliverability reputation splits across two systems: the sending IP and the sending domain. They behave differently, recover differently, and modern mailbox providers weight them differently. Here's what's actually going on and which one to care about.
8 min read
Google Postmaster Tools is the single most important free deliverability tool — and most programs either don't use it or misread the charts. Here's what each tab actually tells you, what to act on, and what to ignore.
9 min read
Gmail's Promotions tab has been polarising since launch — some programs panic about it, others ignore it. The honest answer: it's usually fine, sometimes a problem, and the fix is rarely 'try to avoid the tab'. Here's how to think about it.
7 min read
Seed-list tools (Validity, Litmus, GlockApps) claim to tell you what percentage of your mail lands in the inbox vs spam. The numbers are useful signals but wildly imperfect — and most programs read them more literally than they should.
8 min read
BIMI (Brand Indicators for Message Identification) displays your brand logo next to emails in Gmail, Apple Mail, and Yahoo. The setup is non-trivial and the performance lift is modest. Here's what's required and whether it's worth doing.
8 min read
SMTP error codes are the mechanical reason emails don't arrive. Most programs lump them all into 'bounces' and miss the signal. Here's the actual taxonomy — hard bounce, soft bounce, block, deferral — and what each one tells you.
8 min read
ESPs offer two ways to push mail: SMTP (old, universal, reliable) and API (faster, richer, more work to integrate). Here's which to pick for which scenario and why most programs end up using both.
7 min read
Domain reputation at Low or Bad isn't recoverable in a week. It's a 6–12 week project of disciplined sending to engaged users only, while the reputation signals slowly reset. Here's the structured recovery plan.
9 min read