Mailbox Warm-Up

The short version

New inboxes have no reputation. Send cold emails from one and you land in spam. Kolvera fixes this by sending real, AI-written plain-text conversations between your inbox and other Kolvera users’ inboxes — starting at 2/day and ramping to 20/day over 4 weeks. Pairs rotate weekly for maximum diversity. Inbox placement is tracked per-provider (Gmail vs Microsoft 365) so you know exactly where you stand.

Why does this matter?

Gmail, Microsoft, and Yahoo track every sender’s history. A fresh inbox with zero history that suddenly sends 50 emails gets flagged immediately.

Warming teaches email providers that your inbox is real, active, and sends emails that people actually read and reply to.

How it works

The pool

Your inbox joins a network of real inboxes from other Kolvera users. The system pairs your inbox with up to 20 inboxes at different companies on different domains — so the emails look like natural business conversations, not internal test sends.

Pool membership is automatic — when you start warm-up, your inbox joins. If you leave the pool, warm-up stops, because there are no inboxes to pair with.

Diversity-weighted pairing

The system maximises the number of unique companies your inbox communicates with. Rather than concentrating sends to a few inboxes, pairs are weighted so you send to as many different tenants as possible — exactly what ISPs look for in a legitimate sender.

Pairs rotate every 7 days automatically. Old pairs retire and new ones form, keeping your sending patterns fresh and avoiding the repetitive sender-receiver patterns that trigger spam filters.

Unique plain-text emails

AI writes every warm-up email from scratch using your name, company, and your pair’s details. No templates, no repeated content. Emails are plain text only with no signatures — no HTML formatting, no images, no links. This is how real people email each other casually:

“Hi Sarah, following up on that workforce planning conversation. We’ve been seeing a shift in how mid-market companies approach contingent staffing — curious if you’re seeing the same. Cheers, Dan”

Natural conversation threads

~25% of warm-up emails are replies to existing conversations rather than new threads. This creates realistic 2-3 message chains that look like genuine back-and-forth, not a stream of isolated one-off emails. ISPs weight threaded replies as the strongest engagement signal.

Mimics how you actually email

• Sends at random times during business hours (7am–7pm your timezone)

• 50% volume on weekends — like real people

• Your pair replies back 50% of the time with natural delays (20 min–4 hours)

• If a warm-up email lands in spam, the receiver moves it to inbox — training the filter

• No signatures appended — keeps emails clean and personal

Sent from your actual account

Warm-up emails go out directly from your Gmail or Microsoft inbox via OAuth. Your domain’s DKIM and SPF records are used. The reputation is built on your domain, not a relay service.

Inbox placement tracking

Every warm-up email includes an invisible tracking pixel. When the email is rendered in the recipient’s inbox (not spam), the pixel fires and records an “inbox placement” event.

Your Mailboxes page shows a 7-day inbox placement rate broken down by provider:

• Gmail — inbox rate to Google Workspace and @gmail.com recipients

• Microsoft — inbox rate to Outlook/365 and @outlook.com recipients

• Other — inbox rate to other providers (Zoho, Yahoo, custom hosting)

Target: 80%+ inbox placement across all providers. If one provider drops below 50%, check your DNS records and sending volume.

The ramp schedule

Volume increases automatically each week:

Stage	Days	Emails/Day
Ramp 1	1–3	2	Establishing sender identity
Ramp 2	4–7	5	Reply patterns developing
Ramp 3	8–14	10	Consistent sending history
Ramp 4	15–21	15	Strong engagement signals
Ramp 5	22–28	20	Full volume — ready for campaigns
Maintenance	29+	10	Keeps reputation high alongside campaigns

Weekends and AU public holidays automatically reduce to ~50%. Hard daily cap: 25 sends (safety limit).

DNS records for deliverability

Proper DNS configuration is essential. Without these records, major providers will reject or spam-folder your emails regardless of warm-up.

SPF (Sender Policy Framework)

SPF tells receiving servers which mail servers are allowed to send on behalf of your domain.

                Type: TXT

                Host: @ (or your domain)

                Value: v=spf1 include:_spf.google.com ~all

For Microsoft 365:

                v=spf1 include:spf.protection.outlook.com ~all
            

Using both Google and Microsoft:

                v=spf1 include:_spf.google.com include:spf.protection.outlook.com ~all
            

Only one SPF record per domain. Combine all includes into a single record. Use ~all (softfail) not -all (hardfail) during warm-up.

DKIM (DomainKeys Identified Mail)

DKIM cryptographically signs your emails so receivers can verify they haven’t been tampered with in transit.

Google Workspace:

Admin Console → Apps → Google Workspace → Gmail → Authenticate email
Click “Generate new record” (select 2048-bit)
Add the TXT record to your DNS at the host google._domainkey
Back in Admin Console, click “Start authentication”

Microsoft 365:

Microsoft 365 Defender → Email & collaboration → Policies → Threat policies → DKIM
Select your domain → Enable
Add the two CNAME records shown to your DNS

DKIM is the most important record for warm-up. Without it, your emails will almost always land in spam on Gmail.

DMARC (Domain-based Message Authentication)

DMARC tells receiving servers what to do when SPF or DKIM checks fail, and sends you reports about your email authentication.

                Type: TXT

                Host: _dmarc

                Value: v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

Recommended progression:

• Week 1–4 (warm-up): p=none — monitor only, don’t reject anything

• Week 5–8: p=quarantine; pct=25 — quarantine 25% of failing emails

• After 8 weeks: p=quarantine; pct=100 or p=reject for maximum protection

Start with p=none so you don’t accidentally block legitimate emails while warming up. The rua address receives XML reports showing who is sending email from your domain.

MX records

MX records tell other servers where to deliver mail for your domain. Without valid MX records, some providers will reject your outbound emails.

Google Workspace:

                Priority 1: ASPMX.L.GOOGLE.COM

                Priority 5: ALT1.ASPMX.L.GOOGLE.COM

                Priority 5: ALT2.ASPMX.L.GOOGLE.COM

                Priority 10: ALT3.ASPMX.L.GOOGLE.COM

                Priority 10: ALT4.ASPMX.L.GOOGLE.COM

Microsoft 365:

                Priority 0: yourdomain-com.mail.protection.outlook.com
            

Reverse DNS (PTR record)

If you use Google Workspace or Microsoft 365, reverse DNS is handled for you automatically. This only applies if you run your own mail server.

For custom SMTP: ask your hosting provider to set a PTR record on your sending IP that resolves back to your domain. This is a trust signal that prevents your IP from being flagged as a spam source.

Avoiding spam filters

Beyond DNS, these practices keep your emails out of spam:

Sending practices

• Start slow — never send more than 50 cold emails/day per inbox, even after warm-up

• Spread sends across hours — Kolvera does this automatically with randomised scheduling

• Use multiple inboxes — split volume across 2–3 warmed inboxes

• Monitor bounce rate — pause at 2% and clean your list immediately

• Verify emails before sending — every bounce damages reputation

• Respect unsubscribes — honour them within 24 hours

Content guidelines

• Plain text is king — avoid heavy HTML, images, and fancy formatting in cold emails

• No link-heavy emails — 1 link maximum in cold outreach. Zero is better for the first email

• Avoid spam trigger words — “free”, “act now”, “limited time”, “click here”, excessive caps

• Keep signatures minimal — name + company + one link. Remove banners, images, social icons

• Personalise — use the recipient’s name and company. Generic blasts trigger filters

• Short subject lines — under 60 characters. No RE: tricks or deceptive subjects

Domain hygiene

• Use a separate domain for outreach — e.g. yourcompany.io for cold email, yourcompany.com.au for business. Protects your primary domain if reputation drops

• Age your domain — register outreach domains 2–4 weeks before you start warm-up. Brand new domains are suspicious

• Check blacklists regularly — use the “Check Blacklists” button on your Mailboxes page

• Don’t share IPs — Google Workspace and Microsoft 365 handle IP reputation for you. If using custom SMTP, get a dedicated IP

• Set up a website on your outreach domain — even a simple landing page. Domains with no web presence look suspicious

Maintenance mode

After 28 days of ramping, your inbox enters maintenance mode automatically. Volume drops to 10 emails per day — enough to sustain the reputation you built, without competing with your campaign sends for daily volume.

Keep warm-up running during campaigns. Maintenance emails run in the background alongside your outreach. They provide a steady stream of positive engagement (opens, replies) that offsets any negative signals from cold emails that get ignored or marked as spam.

If you pause warm-up for more than a week or two, your sender reputation will begin to decay. Restarting warm-up picks up where you left off — it does not reset to day 1.

Setup (2 clicks)

1

Connect your inbox via Gmail or Microsoft OAuth

2

Go to Mailboxes → click Start Warm-Up — your inbox joins the pool and pairs automatically

Pairs form when at least 2 inboxes from different accounts are in the pool. Your inbox is added automatically when you start warm-up. Pairs rotate every 7 days for diversity.

What to watch

Your Mailboxes page shows:

• Day & stage — where you are in the ramp

• Sends today — warm-up emails sent vs daily limit

• Next send time — when the next email is scheduled (in your timezone)

• Pairs — how many inboxes you’re paired with (up to 20)

• Inbox placement (7d) — percentage of warm-up emails that landed in inbox, not spam

• Per-provider rates — Gmail, Microsoft, and Other placement rates shown separately

• Deliverability score — DNS, blacklist, and engagement health (0–100)

Tips

• Start warm-up 2–4 weeks before your first campaign

• Keep it running during campaigns — maintenance mode works in the background

• Verify emails before sending — bounces destroy reputation

• Stay under 50 cold emails/day per inbox

• Use 2–3 warmed inboxes and split campaign volume between them

• If bounce rate hits 2%, pause and clean your lists

• Never leave the pool while warming — your inbox needs pool pairs to send warm-up emails

• Disable your provider signature during warm-up (Gmail Settings → Signature → No signature). Warm-up emails are plain text — a branded HTML signature looks unnatural

• Watch per-provider rates — if Gmail drops below 50% but Microsoft is fine, your DKIM for Google may be misconfigured

• Use a separate outreach domain — protects your primary domain reputation

FAQ

Will recipients see warm-up emails in my inbox?

Yes — warm-up emails will appear in your inbox. They’re tagged with -kwu in the subject line. Set up a filter to auto-archive: filter emails with subject containing -kwu → skip inbox, mark as read.

Can I see what warm-up emails look like?

Click “Preview Email” on your Mailboxes page to generate a sample warm-up email for any inbox.

Does warm-up count against my email provider’s daily limit?

Yes. Google Workspace allows 2,000 emails/day and Microsoft 365 allows 10,000/day. Warm-up at full volume (20/day) uses less than 1% of either limit.

What if my inbox placement rate is low?

Check: (1) DNS records are correct (SPF, DKIM, DMARC all passing), (2) domain isn’t on any blacklists (use the Check Blacklists button), (3) domain is at least 2 weeks old, (4) you haven’t sent bulk cold email from this inbox before warm-up completed.

Does warm-up cost credits?

No. Warm-up is included on all plans at no additional credit cost.