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Deliverability fundamentals for cold email

Deliverability is whether your email reaches the primary inbox rather than spam or nowhere at all. For cold email it is the single biggest lever on results: a campaign with 40% inbox placement need…

Draft — written from product facts + domain knowledge; UI labels to be verified before publishing.

Deliverability is whether your email reaches the primary inbox rather than spam or nowhere at all. For cold email it is the single biggest lever on results: a campaign with 40% inbox placement needs two and a half times the volume of one with 100%. This article is the map. Each section links to the article that goes deeper.

The five pillars

1. Infrastructure

  • Send from secondary domains, never your main brand domain.
  • 2–3 mailboxes per domain, spread across several domains.
  • SPF, DKIM and DMARC all passing; MX set; domain forwarding to a real site.
  • A custom tracking domain per sending domain.
  • Icemail sets up all of this automatically for domains bought through it.

2. Reputation (warm-up)

  • Warm up every mailbox 14–21 days before use and keep warm-up on afterwards.
  • Health 85+, inbox placement 95%+, spam placement under 5% before launch.
  • Replace, do not nurse, mailboxes that stay under 70.

3. Volume

  • 30–50 campaign emails per mailbox per day (start at 20).
  • Ramp campaign volume the same way you ramp warm-up: increase weekly, not daily.
  • Set Daily new contacts limit and use a sending schedule with business hours in the recipient's time zone.

4. List quality

  • Verify every list before upload. Bounce rate must stay under 3%; set Pause campaign when bounce rate reaches 3%.
  • Remove role addresses (info@, sales@), catch-all domains you cannot verify, and anyone who has replied "no".
  • Use the global blocklist to keep competitors, customers and unsubscribers out of every campaign.

5. Content and engagement

  • Plain-looking, short (under 120 words), one link at most, no images, no attachments.
  • Personalised with variables and spintext so no two emails are identical.
  • Run the Spam Words check in the editor before saving a step.
  • Include an unsubscribe option (Risk Control → Include Unsubscribe Message / Unsubscribe Header).
  • Replies are the strongest positive signal; a reply rate under 1% means the message, not the mailbox, needs work.

Where each control lives in OutreachFox

**Control****Path**
Buy domains/mailboxes with DNS pre-configuredTop-left icon → **Icemail**
Custom tracking domain**Domain** → domain → **Settings**
Warm-up**Mailbox** → select → **Enable Warm Up**
Per-mailbox daily limit**Mailbox** → select → bulk actions → campaign emails per day
Daily new contacts, bounce pause, plain text, unsubscribe, auto match ESPCampaign → **Edit Campaign** → **Settings** → **Show Advanced Configurations**
Sending schedules**Campaign Settings** → **Sending Schedules**
Spam wordsSequence editor → **Spam Words**
Global blocklist**Settings** → blocklist

Healthy campaign benchmarks

**Metric****Healthy****Act if**
Bounce rate\< 2%\> 3%
Reply rate (any)3–8%\< 1%
Spam complaint rate\< 0.1%\> 0.3%
Warm-up inbox placement\> 95%\< 90%
Open rate (if tracked)40–60%\< 25%

Steps: a 10-minute pre-launch check

  1. Domain → confirm every sending domain has a verified tracking domain.
  2. Mailbox → every sender shows health 85+ and warm-up on.
  3. Campaign → Settings → Show Advanced Configurations: bounce pause 3%, unsubscribe on, daily new contacts limit set, auto match leads on.
  4. Sequence editor → run Spam Words on every step and variant; use Preview to check variables render.
  5. Contacts → list is verified and deduplicated.
  6. Send a test to a Gmail and an Outlook address you own; confirm inbox placement and that authentication headers PASS.

Related articles

  • SPF, DKIM and DMARC: what they are and how to check yours
  • What is mailbox warmup and how it works in OutreachFox
  • How many mailboxes per domain and domains per campaign (best practice)
  • Spam-trigger words and copy checks
  • Blacklist monitoring: how to check and delist a domain or IP
  • Inbox placement testing
  • Global blocklist: exclude domains and emails from all campaigns
  • Landing in spam? The recovery playbook

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More in Deliverability

Spam-trigger words and copy checks→Blacklist monitoring: how to check and delist a domain or IP→Inbox placement testing→Global blocklist: exclude domains and emails from all campaigns→Landing in spam? The recovery playbook→