TL;DR
- Order: authentication, warmup, verified list, slow ramp, watch bounces.
- Keep bounces under 2%; platforms start pausing around 5%.
- No catch-alls on a new domain, and no unverified list, ever.
1. Authentication
- Publish SPF and DKIM for the sending domain, and a DMARC record. Google and Yahoo both require this for bulk senders; see our summary of their rules.
- Check it with the email authentication checker.
- Set up the sending tool's tracking domain, and make sure the From domain aligns with SPF or DKIM.
2. Warmup
- Warm each mailbox before real sends, using your sending tool's warmup or a dedicated service.
- We don't publish a warmup schedule because there is no universal number of days or messages that tools agree on. Follow your tool's guidance.
- Keep warmup running alongside early campaigns if your tool supports it.
3. Verify the list
- Export the leads and verify them in Mail Exchange, even if the source says verified.
- Send only deliverable. Remove undeliverable, disposable and role addresses.
- Hold catch-alls back until the domain has built clean history. See catch-alls.
- Retry unknowns later; they are refunded.
4. Ramp volume slowly
- Start with small daily volume per mailbox and increase gradually. Google's sender guidance says the same for anything that triggers errors: reduce volume, then increase slowly.
- Spread sends across mailboxes and domains so one bad batch cannot sink all.
- Send your most valuable, best-verified leads first, when you can still change course.
5. Bounce thresholds
| Source | Threshold |
|---|---|
| Instantly | Recommends 2% or lower; auto-pauses above 5% after 200 sends (on by default) |
| Smartlead | Under 2% over 14 days is healthy; auto protection is opt-in |
| lemlist | Alert at 10%, pause at 50% after 100 leads |
From each platform's help center or blog, checked 2026-10-17. More in how many bounces burn a domain. Turn on the auto-pause if your tool has it, and look at the first few hundred sends before scaling.
6. Monitor and re-verify
- Check bounce rate per mailbox, not only per campaign.
- Re-verify lists older than about 30 days and before late sequence steps (schedule).
- If you do get burned, see how to recover.