The cold email deliverability checklist
The 10 checks we run before any campaign sends. Authentication, warmup, verification, pacing, and recovery.
Deliverability is binary: your email lands in the inbox or your campaign does not exist. This is the checklist we run before any Agent GTM campaign sends a single message. Steal it.
Before you send anything
1. Authenticate your domain
Three DNS records, non-negotiable. Without them, modern inbox providers quietly route you to spam.
| Record | What it proves | Minimum setup |
|---|---|---|
| SPF | These servers may send for my domain | One TXT record listing your sending service |
| DKIM | This message was not altered in transit | Key published by your email provider |
| DMARC | Here is what to do if a message fails | Start with p=none and a reporting address, tighten later |
2. Use a separate sending domain
Send cold outreach from a cousin domain (for example, tryyourbrand.com), never your primary. If reputation takes a hit, your company email keeps working.
3. Warm up before you ramp
A new domain or mailbox needs two to four weeks of gradually increasing, engaged sending before real volume. Skipping warmup is the fastest way to get filtered on day one.
Before every campaign
4. Verify every address
Bounces are the loudest spam signal there is. Run every list through verification and remove invalid, catch-all-risky, and disposable addresses. Agent GTM does this by default; whatever stack you use, never skip it.
5. Keep volume low and steady
Stay under roughly 30 to 50 cold sends per mailbox per day, spread across the day. Spikes look like spam because spam arrives in spikes.
6. Make the message worth receiving
Relevance is a deliverability feature. Messages grounded in a real signal earn replies, and replies are the strongest positive signal a mailbox provider sees.
7. Give people a clean exit
A plain opt-out line beats a spam complaint every time. Honor opt-outs immediately and suppress them forever.
While campaigns run
8. Watch three numbers weekly
- Bounce rate: under 2 percent, or stop and re-verify.
- Reply rate: under 1 percent means the targeting or message is wrong. Fix it before scaling.
- Spam complaints: above 0.1 percent is a fire alarm.
9. Check your blocklist status monthly
Free lookups against the major blocklists take five minutes and catch problems before they compound.
10. Recover slowly if you get burned
If deliverability tanks: pause, find the cause, cut volume by 80 percent, re-warm on your best segments, and only ramp when replies return. There is no shortcut back.
- SPF, DKIM, and DMARC are the minimum authentication stack for cold email in 2026.
- Verify before send: bounce rate above 2 percent damages sender reputation.
- Safe cold volume is roughly 30 to 50 sends per mailbox per day, warmed and paced.
- Replies are the strongest positive deliverability signal; spam complaints above 0.1 percent are the strongest negative one.
Frequently asked questions
How many cold emails can I send per day in 2026?
Roughly 30 to 50 per mailbox per day once warmed, spread through the day. Need more volume? Add mailboxes and domains, not volume per mailbox.
Do I really need SPF, DKIM, and DMARC?
Yes. Google and Microsoft both enforce authentication for bulk senders, and unauthenticated cold email is filtered by default. It is three DNS records; there is no argument for skipping them.
What bounce rate is acceptable for cold email?
Under 2 percent. Above that, stop sending and re-verify the list. Consistently high bounces mark your domain as a careless sender and the damage compounds.
How does Agent GTM handle deliverability?
Every address is verified before send, volume is paced inside safe limits, and a human approves every campaign, so nothing risky ships. Deliverability is treated as a first-class feature, not an afterthought.