Definition
Email deliverability is the percentage of emails sent that successfully land in recipients' inboxes (rather than spam, promotions tab, or quarantine), driven by domain reputation, authentication, sender behaviour, content, and recipient engagement.
Deliverability is the foundation under every email programme. The best email content fails entirely if it doesn't reach the inbox. Modern email providers (Gmail, Outlook, etc.) use sophisticated reputation models — sender domain age, authentication, engagement rates, complaint rates, list hygiene — to decide where each message lands.
The most common deliverability killers are missing authentication (SPF, DKIM, DMARC), abrupt volume changes, dirty lists with high bounce rates, and content that pattern-matches to spam (excessive caps, link-heavy plain text, image-only emails). Recovering from a damaged sender reputation takes weeks to months — the cost of carelessness on a single send.
Origin
Email's original SMTP protocol (1982) had no authentication. Anti-spam filters arose in the late 1990s. SPF (2003), DKIM (2007), and DMARC (2012) are the layered authentication standards that make modern deliverability possible.
How it works
- Authenticate the sending domain — SPF, DKIM, DMARC. All three.
- Warm up new sending domains gradually (start with low volume, increase over weeks).
- Maintain list hygiene — remove hard bounces, unengaged contacts, complainers.
- Send at consistent volume; sudden spikes look suspicious.
- Watch the metrics: bounce rate, spam complaint rate, engagement rate.
- Monitor blocklists; address listings quickly if they happen.
When to use it
Use when
- Always, on every email programme — marketing, transactional, cold outreach.
- Especially when launching a new domain or new sending IP.
Skip when
- Never "don't". Deliverability is foundational; ignoring it kills the channel.
Key metrics
- Inbox placement rate (most important, often hardest to measure).
- Bounce rate (target under 3%; under 1% is healthy).
- Spam complaint rate (target under 0.1%).
- Open and click engagement (signals reputation to providers).
Examples
- Our deliverability hit 98% after we set up DMARC and warmed the domain for 6 weeks.
- No deliverability, no campaign — it doesn't matter what the email says if it lands in spam.
- Bounce rate dropped from 12% to 2% after the list-cleaning project.
In practice at Makreate
Makreate Email Outreach Automation includes domain warm-up, authentication setup, and reputation monitoring — the foundation under every campaign. A recent client's primary marketing domain had been damaged by years of bad practice — open rates 14%, complaints 0.4%, blocklist appearances. We migrated outreach to dedicated domains, ran a proper warm-up, fixed authentication, and tightened list hygiene. Within six weeks, inbox placement on a Glock test was 96%, replies tripled, and the marketing domain's reputation began healing.
Email Outreach Automation →Common mistakes
- Sending from an unauthenticated domain.
- Skipping warm-up on a new sending domain.
- Sending to old, unverified, or purchased lists.
- Image-only emails — they look like spam to most filters.
- Ignoring engagement signals. Providers downgrade reputation for senders whose recipients don't open or reply.
Frequently asked
How do I check my deliverability?
Tools like GlockApps, Mail-Tester, and Postmark's spam-test service simulate sending to inbox-placement test seeds. Google Postmaster Tools shows real Gmail data for your domain.
Dedicated IP or shared?
High-volume senders (>100K emails/month consistently) benefit from dedicated IPs. Lower-volume programmes do better on reputable shared IP pools.
How long does warm-up take?
2–4 weeks for a new domain, ramping send volume gradually. Shortcut warm-up tools (lemwarm, Mailwarm) automate the process.