Cold email deliverability

What is cold email deliverability?

Cold email deliverability is the subset of email deliverability that applies specifically to unsolicited outbound messages — emails sent to prospects who have no prior relationship with the sender. It's harder than transactional deliverability (receipts, confirmations) or newsletter deliverability (opted-in subscribers) because receiving servers and spam filters apply stricter rules to unknown senders contacting unknown recipients.

For SDRs and BDRs, cold email deliverability is the invisible infrastructure behind every campaign. A rep can write perfect cold emails with a strong first line, sharp value prop, and clear CTA — and have none of it matter if 40% of those emails are landing in spam because the sending domain isn't authenticated or the list hasn't been cleaned.

Cold email deliverability is not set-and-forget. It requires ongoing monitoring: checking bounce rates per campaign, reviewing spam complaint rates in Google Postmaster Tools, rotating mailboxes as domain volume scales, and watching for inbox placement degradation before it becomes a reputation crisis.

Cold email deliverability setup checklist

Before sending the first cold email from any domain, this infrastructure must be in place. Skipping any step degrades inbox placement from the first send.

• Domain setup — use a secondary sending domain (not the primary business domain). Register domains like getgangly.com, gangly-sales.com, or try-gangly.com. Primary domain issues from cold outbound spill over to all email from that domain.
• DNS authentication — configure SPF, DKIM, and DMARC on the sending domain. Verify setup with MXToolbox.com. All three must be active before the first send. Takes 30–60 minutes; required permanently.
• Warmup — start at 5–10 emails per day from a new sending address. Increase by 20–30% per week over 4–8 weeks to reach target volume. Use a warmup tool (Lemwarm, Mailreach, Instantly warmup) to run automated warmup exchanges that build positive engagement history.
• List hygiene — verify email addresses with NeverBounce, ZeroBounce, or Hunter.io before sending. Target: zero known-invalid addresses in the list. Even a 2% hard bounce rate is enough to start damaging domain reputation.
• Mailbox limits — never send more than 30–50 cold emails per day per mailbox. At higher volume, add more mailboxes with separate warmup history rather than exceeding per-mailbox limits.
• Monitoring — set up Google Postmaster Tools for each sending domain. Check spam complaint rate weekly. Check bounce rate per campaign. Use GlockApps to test inbox placement before each new campaign launch.

Common cold email deliverability mistakes

1. Sending from the primary company domain. One spam complaint storm on your outbound domain can affect your company's transactional email — password resets, invoices, support tickets. Keep outbound on secondary domains.

2. Buying a list and emailing it immediately. Purchased lists have high invalid address rates (5–20%) and often contain spam traps — email addresses specifically designed to catch bulk senders. Even one hit on a spam trap can blacklist the sending domain. Never send cold email to a purchased list without verification and warmup.

3. No warmup on new mailboxes. New Google Workspace or Microsoft 365 accounts sending 100+ emails on day 1 get flagged by every major ISP. Gmail may suspend the account; Outlook may start routing everything to junk.

4. Volume spikes. A domain that averages 30 emails per day suddenly sending 300 triggers anomaly detection. Volume growth should be gradual — no more than 20–30% per week.

5. Ignoring engagement signals. If recipients are consistently not opening emails (low open rate) and not replying (low reply rate), spam filters learn that recipients don't want email from this domain. Engagement — even clicks without replies — signals that the emails are wanted.

How Gangly's send model supports cold email deliverability

Gangly generates outreach that sends through the rep's connected inbox (Gmail or Outlook), one message at a time, reviewed before sending. This send model produces engagement patterns that look like genuine 1:1 correspondence — because it is — rather than automated mass campaigns. Each message goes from a real rep's address, to one specific prospect, with a specific reason for reaching out.

The Workflow Sequencer controls cadence so that daily send volume per mailbox stays within safe limits naturally. A rep who approves and sends 20–40 Gangly-drafted messages per day generates normal sending patterns rather than the burst behavior that triggers spam filters.

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Frequently asked questions