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When to use high-volume sending

Use High-volume email sending when you see throttling, delayed delivery, or reduced deliverability using inbox-based sending (Microsoft/Google). This option is designed for transactional / recruiting outreach at scale, while still sending from your domain.

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This setup requires DNS changes

Unlike inbox-based sending (Microsoft/Google OAuth), high-volume sending requires updating your DNS so Tenzo can:
  • Send authenticated email from your domain (SPF/DKIM)
  • Receive candidate replies so Tenzo can continue the conversation

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What this changes (and what it doesn’t)

  • From: candidates see emails coming from the recruiting email address you configure (e.g. morgan@recruiting.company.com).
  • Reply experience: candidates can hit “Reply” normally and Tenzo will receive replies to continue the conversation.
  • Inbox visibility: emails are not sent “from an employee mailbox” (so they may not appear in Outlook/Gmail Sent Items).

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Optional: use a subdomain

Using a subdomain is optional, but it’s often a good idea because it can:
  • Isolate reputation: keeps recruiting/outreach traffic separate from your main corporate email traffic
  • Reduce operational risk: makes it easier to roll back or adjust recruiting email settings without touching your primary domain
  • Simplify deliverability work: clearer DNS/auth boundaries for recruiting email
Examples:
  • morgan@recruiting.company.com
  • recruiting@company.com

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DKIM selector conflicts (SendGrid)

Some customers already have DKIM records on their base domain from other email providers. SendGrid’s default DKIM selectors (s1 / s2) can conflict with those existing records. Tenzo automatically generates a unique DKIM selector for your setup to avoid collisions. Also, SendGrid may return DKIM CNAME hosts on the base domain even if you’re sending from a subdomain — that’s expected; just add the DNS records exactly as shown in Tenzo.

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Setup steps

  1. In Tenzo, go to Admin → Office Integrations → Email Integrations
  2. Select High-volume sending (Recommended)
  3. Enter your recruiting email address
  4. Click Begin setup
  5. Add the DNS records Tenzo shows (SPF/DKIM and inbound routing records)
  6. After DNS propagates, click Check DNS
High-volume sending setup screen

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DNS records (what they do)

Tenzo will show the exact DNS records to add. Common records include:
  • DKIM (CNAME): enables cryptographic signing for your domain
  • SPF (TXT): authorizes Tenzo’s sending infrastructure for your domain
  • Inbound routing records: allow Tenzo to receive replies
DNS records table for high-volume sending

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Why inbox-based sending can throttle at high volumes

When you connect an individual inbox (or domain-wide access), Tenzo is sending “as a mailbox user” in Microsoft/Google. Those providers apply per-user/mailbox sending limits and anti-abuse controls that can trigger throttling. Typical caps (varies by tenant/account and can be lower in practice):
  • Google Workspace (Gmail): up to ~2,000 recipients/day per user (consumer Gmail accounts are typically lower, ~500/day)
  • Microsoft Exchange Online: published limits can be higher (e.g. ~10,000 recipients/day), but practical anti-abuse limits for external recipients may be much lower for some tenants/mailboxes (for example, you may see alerts around a few hundred external recipients/day).

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Troubleshooting

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DNS says “not verified”

  • DNS changes can take time to propagate; try again in 10–30 minutes.
  • Double-check there are no typos in Host/Value.