Cold Email Deliverability That Protects Your Pipeline
One burned domain can stall a whole pipeline. Volume without reputation is just spam. Warmy is the email deliverability platform behind cold email outreach. It warms up multiple mailboxes, watches the health of every sending domain, checks your templates for spam triggers and runs Inbox Placement Tests before every campaign. The result: cold emails that reach the primary inbox, not the spam folder.
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<25 sec
Average setup time
1M+
Real mailboxes in the warm-up network
120+
Deliverability specialists on the Warmy team
650K+
Domains with improved deliverability
TRUSTED WORLDWIDE
Trusted By High-Volume Outbound Teams
What Is Cold Email Deliverability?
Cold email deliverability refers to the share of your cold emails that reach the recipient's inbox, not the spam folder or the promotions tab. With no engagement history to lean on, mailbox providers judge every cold email on sender reputation, authentication and list quality.
Warmy handles that side for you, underneath the sequencer or email service provider you already use.
Cold emailWhy Cold Email Outreach Breaks On Infrastructure
Cold outreach goes to people who have never heard from you. There's no engagement history; every send comes from a low-reputation domain, and mailbox providers have every reason to be cautious. That's why cold email deliverability is the first thing to fail when outbound scales.
0.3%
Spam complaint rate Gmail and Yahoo require bulk senders to stay below (aim for under 0.1%)
5,000+
Emails a day that make you a bulk sender at Gmail and Microsoft
3
Authentication protocols mailbox providers require from bulk senders: SPF, DKIM and DMARC
1. One burned domain can stall the pipeline
Most teams run cold email from a handful of secondary domains and multiple mailboxes. When one domain's reputation drops, replies stop and meetings dry up. If several mailboxes share the same domain, they all go down together. You often find out weeks later, from the pipeline report.
2. Volume without reputation is spam
A new domain has no history. Push hundreds of cold emails a day through it in week one, and mailbox providers treat the spike as a spam signal. Domain age, a gradual ramp, and steady positive engagement earn you the right to send cold email volume.
3. Small setup mistakes trigger spam filters
A missing DKIM record, a shared tracking domain, an unverified list or a template full of spammy words can each push a cold email campaign into spam. None of them show up in your sequencer's dashboard, which only tells you the email was sent.
One Deliverability Platform Behind Every Cold Email Campaign
Warmy runs underneath your cold email stack. It doesn't write or send your outreach. It makes sure Gmail, Outlook and Yahoo trust every sending domain and mailbox when your sequence goes out.
1. Warm up multiple mailboxes at once
Mailboxes in Warmy's 1M+ warm-up network of real Google Workspace, Microsoft 365 and consumer inboxes open your emails, reply to them and move them out of spam. Each mailbox gets its own warm-up schedule, which runs during working hours in the recipient's time zone and keeps going while you send. Warm-Up with Clicks adds scrolling and link clicks for emails that carry links, like booking pages.
2. Protect domain reputation across your rotation
Rotation only spreads risk if every domain in it is healthy. Warmy tracks domain and IP reputation, blocklist status and Google Postmaster data for each sending domain, with alerts the moment one slips, so you can pause it before it drags down the rest.
3. Spam-check email templates before they ship
The Templates AI optimizer scores your email templates and rewrites the parts most likely to trigger spam filters. Adeline, Warmy's AI email deliverability agent, reads your test, DNS and warm-up data and tells you what to fix next.
4. Run placement tests before every campaign
Run an Inbox Placement Test on your real template before you launch or scale a cold email campaign. See whether it lands in the primary inbox, the Promotions tab, spam or goes missing at each provider. Each test lets you collect data on placement before real prospects ever see the email. Email providers filter differently, so placement can vary a lot across different providers.
5. Check DNS records and authentication
DNS health checks and DMARC monitoring show whether SPF, DKIM and DMARC are set up and aligned for every email domain, and tell you exactly which record to change when something breaks.
6. Verify lists before they hit a sequence
Built-in email verification checks syntax, MX records, and mailboxes, and flags catch-all, disposable, and role addresses, as well as known spam traps. Remove them before they bounce and cost you sender reputation.
Get a deliverability plan built around your domains, mailboxes and daily cold email volume.
The Cold Email Infrastructure Checklist
Good cold email infrastructure is the most reliable method to improve cold email deliverability. Here's the setup that protects your sending reputation, and where Warmy fits into each step.
- What good looks like
- Send from secondary domains close to your brand name, never your primary domain, so your company’s main email domain stays clean.
- How Warmy helps
- Health data and alerts for each sending domain
- What good looks like
- Spread volume across multiple mailboxes on multiple domains instead of pushing more through one.
- How Warmy helps
- Separate warm-up schedule and health data for every mailbox
- What good looks like
- SPF, DKIM and DMARC published and aligned on every sending domain.
- How Warmy helps
- DNS health checks and DMARC monitoring with the exact record to change
- What good looks like
- Set up custom domain tracking: a custom tracking domain on your own subdomain instead of your sequencer's shared one. Or switch link and open tracking off.
- How Warmy helps
- Inbox Placement Tests show where emails with tracked links land
- What good looks like
- Two to four weeks of warm-up before a new domain sends cold email, then keep warm-up running.
- How Warmy helps
- Automated warm-up in a 1M+ real-mailbox network
- What good looks like
- Verify every contact so only real email recipients enter a sequence.
- How Warmy helps
- Built-in email verification
- What good looks like
- Plain, short email templates with no spam trigger words.
- How Warmy helps
- Templates AI optimizer and Adeline
- What good looks like
- Watch reputation, blocklists and placement continuously, not after a drop.
- How Warmy helps
- Reputation tracker, blocklist alerts and placement tests
Write Cold Emails Spam Filters Trust
Bad copy can sink a good domain. Keep every cold email template plain and personal, not like marketing emails. Warmy's Templates AI optimizer scores each template and rewrites what trips spam filters, and an Inbox Placement Test confirms where it lands before you launch.
Subject lines
- Short, specific and written the way a colleague would write it
- No all caps, hype or fake "Re:" prefixes
- Test email subject lines for cold emails in the Template Checker
Cold email format
- One plain email template for cold email outreach per audience
- Plain text that renders in all email clients, with no spelling errors
- One link and an easy way to opt out, like an unsubscribe link
- Run a sample cold email through an Inbox Placement Test first
Follow-ups that let people opt out
- Same thread, a few days apart
- Stop the moment someone replies or opts out
- Each follow-up has to land in the inbox as reliably as the first email
Avoid spam trigger words
- Cut phrases like "act now" or "100% guaranteed"
- Avoid spammy words in links and signatures too
- Skip stacked exclamation marks and money symbols
Every Cold Email Touch, Actually Delivered
Every step of a cold email campaign depends on inbox placement. Warmy protects all of them.
First touch
Your first cold email only gets a chance if it comes from a warmed, authenticated domain. Warm-up and an Inbox Placement Test give it a real shot at the primary inbox.
Follow-up steps
Placement often drops later in a sequence, as volume builds and engagement thins. Keep warm-up and monitoring going so every cold email follow-up lands where the first one did.
New sending domain launches
Adding domains to grow cold email volume? Warm each new domain for two to four weeks before it joins the rotation, and confirm placement before it sends at full volume.
Rotation across multiple domains
Rotating across dozens of mailboxes and domains only works if you warm, authenticate and monitor each one. Warmy flags weak mailboxes before they hurt the rest.
Replies and meetings
Meeting links, confirmations and handoffs to a rep are where deals move forward. They can't sit in spam either.
Re-engaging older lists
Old lead lists carry dead addresses and spam traps. Verify them before you send, then test placement on a small batch first.
Works With The Cold Email Tools You Already Use
Warmy works with any sending platform. No migration, no new sequencer and no changes to your workflow. Connect in one of three ways:
Direct connection:
Google Workspace, Microsoft 365, any SMTP/IMAP mailbox or platforms like Outreach, Apollo.io, ZoomInfo, HubSpot and GoHighLevel.
API and automation:
connect mailboxes and manage warm-up through the Warmy API or automate with n8n, Zapier or Make. Cold outreach platforms and ESPs already run their warm-up on it.
Seed List:
add Warmy's addresses to your own email service provider when a platform can't be connected directly. Emails sent to them are opened, scrolled and clicked.
- Google Workspace
- Microsoft 365
- Any SMTP or IMAP mailbox
- Outreach, Apollo.io, ZoomInfo, HubSpot, GoHighLevel
- API, n8n, Zapier, Make
- 70+ integrations for B2B senders
Your Sequencer Sends The Email. Warmy Gets It Delivered.
- Audience
- Your sequencer or email outreach tool: Lead lists, prospect data and personalization
- Warmy: Email verification that removes invalid and risky addresses first
- Message
- Your sequencer or email outreach tool: Email templates, cold email subjects and variables
- Warmy: Templates AI optimizer and Inbox Placement Tests before you send
- Sending
- Your sequencer or email outreach tool: Scheduling, sending limits and mailbox rotation
- Warmy: Warm-up for every mailbox, before and during live sending
- Ongoing
- Your sequencer or email outreach tool: Replies, follow-ups and reporting
- Warmy: Reputation, blocklist and DMARC monitoring with alerts, plus Adeline when something slips
A great cold email in spam is still unread. Warmy keeps the outgoing email side healthy so your copy gets a fair hearing with its intended recipients.
What Better Cold Email Deliverability Is Worth
Deliverability sits under every other number. When more of each sequence reaches the inbox, you get more opens, replies and positive responses, and future campaigns start from a stronger sending reputation.
2.3×
Higher open rates
95%
Inbox placement
−35%
Lower bounce rates
Illustrative example based on typical lift. Actual results depend on list quality, content and sending history.
Key Metrics To Monitor Email Deliverability
- Inbox placement rate:
- how much of each cold email campaign lands in the inbox at each provider
- Bounce rate:
- list quality and data freshness
- Spam complaints:
- how often you're marked as spam (keep it well under 0.3%)
- Reply rate and positive response rate:
- whether the right people see and act on your email outreach
- Domain and IP reputation:
- Google Postmaster data, blocklist status and third-party scores like Sender Score
- Authentication status:
- SPF, DKIM and DMARC passing on every sending domain
Warmy shows the deliverability side of these key metrics, so you can tell a copy problem from an email reputation problem.
Deliverability For Every Cold Email Sender
Founders and small sales teams
Sending cold emails yourself? Connect a mailbox, let warm-up and monitoring run in the background, and get a plain answer from Adeline when something slips.
SDR and outbound teams
Run dozens of mailboxes across multiple domains with per-mailbox warm-up, placement tests before new sequences go live and alerts the moment a domain slips. Running AI agents? See Warmy for AI SDRs.
Cold email agencies
A cold email agency can connect each client's mailboxes, warm them up, test placement and monitor reputation from one agency account, with access controls and shareable results for each client. See Warmy for agencies.
Lead generation and recruiting
Outreach to new contacts needs clean lists and steady placement. Verify, warm up and test before each new campaign.
"I've already gotten a handful of legit meetings from Warmy based just on cold emails, and the messaging hasn't changed much from what we were using before."
Jesse Vogt, Director of Business Development
See All Success StoriesFAQs About
Cold Email Deliverability
Your Email Strategy Is Only As Good As Your Infrastructure
Cold email isn't the same job as sending marketing emails to subscribers. Nobody asked for your first message, your domains are young, and one careless send can burn a domain your pipeline depends on.
Warmy is the platform that handles it: continuous warm-up for every mailbox, inbox placement testing, reputation and blocklist monitoring, authentication checks, list verification and template scoring across every domain you send from. It's built by 120+ deliverability specialists, so your team can focus on conversations instead of DNS records.
FREE TOOLS
Test Your Cold Email Deliverability With Our Free Tools
Check every cold email before it reaches a prospect:
run a quick deliverability check on your email
check your subject line and copy for spammy words
see your template's estimated spam score before you send
get an A to F reputation grade for your sending domain
see if your domain is on a blocklist
validate your DMARC record
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Stop Losing Pipeline To Spam Folders
Book a 30-minute demo. Share your domains, mailbox count and daily volume, and we'll show you where your cold emails land today, what's holding placement back and how to fix it, step by step.
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