If you’re sending cold emails for B2B outreach and keep landing in spam, you know the pain: zero replies, weird bounces, and that sinking feeling your efforts are being torched by Gmail and Outlook. This guide is for people who want to actually get their emails seen, not just sent. I’ll walk you through how to use Warmupinbox to fix spam folder problems—without the fluff.
Why Your B2B Cold Emails Go to Spam (and Why You Should Care)
Let’s get the obvious out of the way: most cold emails go straight to spam. Why? Email providers like Google and Microsoft are paranoid about spam, and rightfully so—everyone’s inbox is under siege. But this means your carefully crafted outreach often gets filtered, even if your intentions are good.
The main culprits: - Brand new domains or mailboxes with no history - Sudden spikes in sending volume (sending 200 emails on day one) - No real people replying to your emails - Bad domain setup (missing SPF, DKIM, or DMARC records) - Repetitive or “salesy” language that triggers spam filters
You can write the best copy in the world, but if your technical setup is off—or your domain looks suspicious—it won’t matter.
What Is Warmupinbox, Really?
Warmupinbox is a tool that helps “warm up” your email account. In plain English, it slowly sends and receives emails between real (or at least convincingly real) mailboxes, making your domain look more trustworthy in the eyes of spam filters.
Here’s what it actually does: - Sends and receives real emails from your account to others in a network - Replies to some of those emails to show “engagement” - Automatically removes your emails from spam if they land there - Gradually increases sending volume to mimic normal human behavior
It’s not a silver bullet, but if you’re getting started with a new domain or your deliverability has tanked, it can help “rehabilitate” your sender reputation.
Step 1: Set Up Your Domain and Email Properly (Don’t Skip This)
Before you touch Warmupinbox, make sure your domain and email are set up right. Warmup tools are not magic—they won’t fix broken DNS records or sloppy setups.
Checklist: - Own your sending domain. No “@gmail.com” or random free accounts. - Set up SPF, DKIM, and DMARC. These DNS records tell other mail servers you’re legit. - Use tools like MXToolbox or Google’s admin checker to verify your setup. - Set up a dedicated sending mailbox. Don’t use your main account for cold outreach.
Pro tip: If your domain is less than a few months old, don’t expect miracles. New domains are automatically suspicious.
Step 2: Sign Up and Connect Your Mailbox to Warmupinbox
Go to Warmupinbox and create an account. The process is straightforward, but don’t rush connecting your mailbox.
What to do: 1. Log in and follow the prompts to add your email account. You’ll need to grant access (OAuth or app password, depending on your provider). 2. Choose the mailbox you plan to use for outreach—not your personal or main sales inbox. 3. Double-check permissions; you’re letting a third party send/receive emails as you.
What not to do: - Don’t connect mailboxes you use for sensitive, internal conversations. Warmupinbox’s network is generally safe, but better to be cautious.
Honest take: Connecting via OAuth (Google or Microsoft login) is easier, but app passwords can be safer if you’re security-conscious.
Step 3: Configure Your Warmup Settings (Start Slow)
This is where a lot of people mess up—they crank up the sending volume and get flagged as bots.
Suggested settings for new mailboxes: - Start with 5-10 warmup emails per day. - Gradually increase by 2-5 emails every few days, not all at once. - Set a realistic “max” (no more than 40-50/day for new domains).
Don’t bother with: - Customizing the warmup messages. Nobody reads them, and they’re meant to be generic. - Aggressively increasing daily limits. More isn’t better—it’s riskier.
Pro tip: Let the warmup run for at least 2-4 weeks. Impatience is the fastest way to trigger spam filters.
Step 4: Monitor Results and Check Your Sender Reputation
Don’t just “set and forget.” Check if your emails are actually avoiding spam.
How to track progress: - Use Warmupinbox’s dashboard to see where your emails are landing (Inbox, Promotions, Spam). - Watch for consistent inbox placement before scaling outreach. - Check your domain’s reputation using services like Google Postmaster Tools or Talos Intelligence.
If you’re still hitting spam after a couple of weeks: - Double-check your DNS records. - Make sure you’re not using blacklisted links or attachments in your templates. - Consider slowing down the warmup.
Red flags: - Warmup emails still land in spam after 30+ days. - Reputation tools show “bad” or “low” scores.
Step 5: Start Sending Real Outreach—But Don’t Go Nuts
Once your warmup is showing consistent inbox placement, you can start sending real cold emails. But be careful—don’t flood your new mailbox.
Best practices: - Start with small, targeted batches (20-30 emails/day). - Space out emails—avoid blasting hundreds at once. - Keep your messaging personal and relevant; avoid spammy phrases (“guaranteed,” “money back,” etc.). - Keep running Warmupinbox alongside your outreach. This helps maintain a healthy sender reputation.
What to ignore: - Overly complicated “personalization hacks.” Focus on relevance and clarity, not gimmicks. - Any advice that suggests sending hundreds of emails per day from a fresh domain.
Pro tip: If you need to scale, consider spreading outreach across multiple warmed-up mailboxes, not just one.
Step 6: Keep It Going—And Know When to Stop
You don’t need to run Warmupinbox forever. Once your outreach is humming along and inbox placement is steady, you can dial back the warmup.
When to taper off: - After 1-2 months of consistent inboxing and solid reply rates - If you’re only sending a handful of emails per day
But if you ramp up volume or see spam issues creeping back, restart the warmup—don’t wait until deliverability tanks.
What Works, What’s Overhyped, and Common Mistakes
What actually helps: - Consistency. Slow, steady warmup beats “big bang” approaches every time. - Realistic sending volumes. Don’t try to outsmart spam filters—they’re better than you think. - Ongoing monitoring. Catch deliverability issues early.
What’s overhyped: - “Inbox placement guarantees.” No tool can promise 100% inbox—run from anyone who says otherwise. - Over-personalized warmup emails. The content doesn’t matter; the activity does.
Common mistakes: - Skipping DNS setup. If SPF/DKIM/DMARC are wrong, nothing else matters. - Impatience. Trying to “rush” warmup almost always backfires. - Using warmup as a crutch for bad lists or spammy templates.
Wrapping Up: Keep It Simple, Iterate, and Don’t Overthink It
Here’s the real secret: focus on the basics, be patient, and keep an eye on your results. Warmupinbox is a helpful tool, but it’s not magic—you still need to send good emails from a properly set up domain. Start slow, monitor your reputation, and adjust as you go. If something feels sketchy or too good to be true, it probably is.
Get your setup right, let the warmup do its thing, and focus your energy on writing emails people actually want to read. That’s how you stay out of the spam folder—no tricks required.