outreach-deliverability

Overview

Outreach fails silently when mail lands in spam. Deliverability is infrastructure plus behaviour: authenticated sending domains, gradual volume, clean lists, and messages that readers do not mark as spam. This skill specifies the setup and the diagnostic order. It designs and diagnoses; it does not send.

Mailbox-provider rules change. The figures below are the commonly cited working norms; confirm against the current Google, Yahoo, and Microsoft sender guidelines before committing a plan.

Mental model

Mailbox providers score sender reputation from authentication, complaint rate, bounce rate, and engagement. Reputation attaches to the domain and the IP. A cold campaign borrows reputation; a complaint spike spends it. Protect the primary domain by sending outreach from separate domains.

Rules

Infrastructure

• Separate sending domains for outreach, never the primary company domain. Close variants of the brand are common practice.
• Each sending domain has SPF, DKIM, and a DMARC record. Start DMARC at p=none with reporting, aligned with the From domain.
• A few mailboxes per domain, each with a real name and signature. Do not spread volume across dozens of throwaway domains.
• Bulk-sender rules: Google applies them at about 5,000 messages a day to personal Gmail accounts, Yahoo to bulk senders without a published number, and Microsoft at 5,000+ a day to Outlook.com since 5 May 2025. All three require SPF and DKIM passing plus an aligned DMARC record.
• Gmail and Yahoo also require one-click unsubscribe on marketing mail, and cold outreach counts: RFC 8058 List-Unsubscribe plus List-Unsubscribe-Post: List-Unsubscribe=One-Click, honoured within 2 days.

Warmup and volume

• Warm new domains 2 to 4 weeks with low, rising volume and real replies before campaign traffic.
• A cap in the region of 30 sends per mailbox per day is a practitioner norm, not a provider rule. Raise it only while metrics stay healthy.
• Sudden volume jumps are a spam signal. Ramp gradually.

Hygiene

• Verify addresses before sending. Target bounces under about 2%.
• Remove hard bounces, unsubscribes, and complaints immediately and permanently.
• No purchased lists and no scraped lists with unclear provenance.
• Never re-contact someone who opted out, on any domain or sequence.

Content

• Plain text, one link, no attachments, no open-tracking pixel on first touch.
• No spam trigger words and no misleading subjects.
• Individual copy: identical bodies at scale are easier to cluster and filter.

Targets and thresholds

Diagnostic order

When mail is not landing, check in this order and change one thing at a time:

1. Authentication: SPF, DKIM, DMARC pass and align.
2. Domain age and warmup state.
3. List quality and bounce rate.
4. Volume and sending pattern.
5. Copy: spam words, links, tracking, length.
6. Complaints and blocklists.

Shared rules

Use the outreach-cold-copy skill for the message itself and the outreach-compliance skill for consent and opt-out rules.

Examples

Bad: "Send 500 a day from our main domain starting tomorrow."

Good: "Two new domains, two mailboxes each, SPF/DKIM/DMARC live, 3 weeks warmup, then 20 sends per mailbox per day on a verified list, stopping if complaints pass 0.1%."

Checklist

• Outreach sent from separate domains, not the primary one?
• SPF, DKIM, and DMARC pass and align on each sending domain?
• Warmup of 2 to 4 weeks before campaign traffic?
• Lists verified, bounces under about 2%, opt-outs suppressed permanently?
• Complaint threshold and a kill rule defined?
• Current provider guidelines re-checked rather than relying on this list?

Composition / References

• Pair with outreach-cold-copy and outreach-compliance.
• This skill covers email only. LinkedIn automation violates its User Agreement; keep those touches manual.