Recruiting is a volume game played with cold email. Sourcing outreach to passive candidates runs into the same filters that evaluate every other cold-email program — but with the added twist that recruiters often also send transactional email (interview confirmations, feedback forms, offer letters) from the same domain. When the cold side is noisy, the transactional side suffers. Candidates miss offer letters they were told to expect. Deal close rates drop for reasons that look like "candidate lost interest" and are actually "candidate never got the email."
Separate sending identities for sourcing outreach and transactional candidate mail. Warm the outreach domain before scaling. Use offers.firmname.com or a separate ATS integration for any candidate transactional mail so offer letters and interview confirmations never ride the outreach reputation. Seed-test weekly, and specifically test to Gmail consumer and Outlook.com — where passive candidates actually read mail.
Two workloads, two reputations
Recruiters run two distinct email workloads:
- Sourcing outreach: cold email to passive candidates. High volume (50–500 sends per recruiter per day), personalised but with a pattern ("saw your background in X, have a role at Y"), reply-rate driven.
- Transactional candidate mail: interview scheduling, interview confirmations, feedback requests, offer letters, onboarding instructions. Low volume per candidate, zero tolerance for delivery failure.
Running both from recruiter@firmname.com is the default. It's also why offer letters land in spam: a recruiter whose outreach reputation has accumulated complaint signals from low-engagement cold email can't send a clean offer-letter email from the same domain.
Sourcing outreach deliverability
The outreach stream is subject to the same rules as any cold-email program, with a few specifics:
Sending domain
Do not use the main firm domain for cold outreach. Register a close-variant domain (the firm is greenhillcap.com; use greenhillcap-talent.com or hellogreenhill.com) and send exclusively from there. Warm the domain for 3–4 weeks before scaling. Any reputation damage stays isolated from the firm's main domain and its transactional mail.
Volume per sender
Per-recruiter send volume should stay under 50/day during warm-up and under 200/day at steady state. Above 200/day from a single sender, reply rate collapses and complaint rates climb. Better to have three recruiters at 150/day each than one recruiter at 450.
Personalisation that actually counts
Spam filters notice near-identical messages sent at volume. Personalisation that moves the needle is specific: the candidate's recent project, their current employer, something they wrote or shared publicly. Personalisation that doesn't move the needle: {FirstName}, current title, years of experience. Filters have seen those merge fields for 20 years.
Reply patterns
Low reply rate is itself a filter signal. If your outreach is at 2% reply, the pattern looks like spam even if the content is fine. Higher reply rate — through better targeting, not more volume — improves deliverability. The first fix for an outreach program that's losing ground isn't more sending; it's better lists.
Offer letters and the transactional side
An offer letter reaching spam is the single worst failure mode in recruiting. The candidate who was told "look for an email from us by 5pm" and doesn't see it by 5:15 starts wondering if the offer fell through. By the time they check spam the next morning (or don't), the candidate experience is already damaged and a competing offer may have arrived clean in their inbox.
Architecture that prevents this:
- Offer letters and transactional candidate mail route through the firm's main domain, not the outreach domain. Ideally through a subdomain like offers.firmname.com with dedicated sending and a warm reputation.
- ATS integration matters. If your ATS (Greenhouse, Lever, Workday, iCIMS) sends from a shared pool, configure branded sending on your domain. Every modern ATS supports this.
- DKIM alignment end-to-end. The candidate sees from: Sarah Chen <sarah@firmname.com> with DKIM signed by firmname.com. Gmail and Outlook both weight this heavily for transactional mail.
Before the first real offer goes out on a new ATS integration or sending configuration, send the template through Inbox Check. You'll see where it lands at every major receiver, and you'll catch problems before a candidate's experience pays the price.
The Gmail Promotions trap for recruiters
Passive candidates read mail on their phones during commutes. The Gmail mobile app shows the Primary tab by default; Promotions is a separate tab that most users don't check more than once a week. A sourcing email in Promotions is effectively invisible.
Signals that push recruiter email to Promotions:
- Email signature with a big logo, job-board banner, or tagline image.
- Multiple links in the body (to the job post, to your LinkedIn, to Calendly, to a careers page).
- A "View Job" button rendered as a coloured CTA.
- An unsubscribe footer with lots of boilerplate.
The sourcing email that consistently lands in Primary looks like a short email from a human: 80–150 words, text only, one link at the bottom, a plain text signature. The visual polish that feels "professional" is the same polish that signals "marketing" to Gmail.
Interview confirmations and Calendly
Most recruiters use Calendly, SavvyCal, or an ATS-integrated scheduler for interview booking. The confirmation emails from these tools often come from a shared sending domain ("calendly.com" or the ATS vendor's domain). That's usually fine for reputation but bad for candidate experience — the candidate sees an unfamiliar sender and is more likely to miss the confirmation.
Fix: configure custom-domain sending in the scheduler (Calendly Pro+ supports it) so confirmations come from interviews.firmname.com. Calendar invites continue to work regardless — the iCal attachment and the scheduling logic are independent of the email sender.
Staffing and placement teams
Staffing firms (as opposed to executive search) often operate with different mechanics: higher volume, more candidates in the pipeline at any time, shorter-term placements. Deliverability patterns:
- Availability blast emails to a candidate bench ("We have a 3-month contract in Dallas starting Monday — reply if interested"). These blur the line between transactional and marketing. Treat them as marketing for deliverability purposes: use a proper ESP, include unsubscribe, send from a marketing subdomain.
- Client-side communication is typically B2B to corporate Microsoft 365 tenants. Different filter dynamics from consumer Gmail — DMARC alignment matters more, content filtering matters less.
- Contract documents and W-9 collection should never go as email attachment. Use an e-signing platform (DocuSign, HelloSign) that sends its own confirmation emails with proper authentication.
The "candidate ghosted us" misdiagnosis
A candidate who stops responding mid-process looks like ghosting. Sometimes it is. Often, a message in the middle of the sequence landed in spam and the candidate never saw the follow-up. The recruiter assumes disinterest; the candidate assumes the recruiter lost interest. Both sides drift away from a process that would have closed if the email had arrived.
Practical check: the third email in a sequence to a non-responsive candidate often has worse deliverability than the first (pattern repetition, filter suspicion). Running the sequence through a seed test from the recruiter's own sending path catches this.