Inboxy Review: Email Warmup Tool on AppSumo Worth It?

Why Email Warmup Matters

If you haven't been doing much email marketing lately — or you've just set up a fresh domain — you can't simply flip a switch and start blasting out thousands of emails. Going from zero to 10,000 sends overnight is one of the fastest ways to tank your deliverability, even if every single one of those emails is completely legitimate.

Email service providers like Google and Microsoft are watching for exactly this kind of behavior. When they see a brand-new address suddenly pushing out huge volumes, it triggers spam filters almost immediately. The fix? You need to gradually warm up your sending reputation so that providers learn to trust your domain.

That's where a tool like Inboxy comes in. It automates the warmup process by sending emails on your behalf to a network of managed inboxes, simulating real human email activity. Over days and weeks, this builds up your sender reputation so that when you're ready to send at scale, your emails actually land in the inbox.

Plans and Pricing

Inboxy is available on AppSumo starting at $59 for a one-time lifetime deal. Every plan includes the same core features — the only difference between tiers is how many inboxes you can warm up simultaneously. The base tier covers one inbox with up to 120 emails sent per day, while the highest tier (tier five) supports up to 20 managed inboxes.

One detail worth highlighting: you can swap out inboxes once they're warmed up. This makes Inboxy viable as a service you could offer to clients. Warm up three to five inboxes at a time, finish the process, then rotate in the next batch. For agencies or freelancers handling multiple client accounts, that flexibility adds real value to even the lower tiers.

Connecting Your Inbox

Getting started with Inboxy is straightforward. After activating your AppSumo code, you're taken through account creation and can immediately begin connecting inboxes. The platform supports Google (personal Gmail and Workspace via OAuth), Microsoft, Mailgun, GoDaddy, SendGrid, Inbox Road, and custom SMTP.

For anyone running cold outreach from their own mail server, the custom SMTP option is the way to go. You'll need your server's SMTP credentials and the correct port configuration — which may take a bit of troubleshooting depending on your provider. If you're connecting through Google or Microsoft, it's much simpler: just click a button and authorize through OAuth.

One thing to note: the older browser-based authentication method for Gmail and Workspace is being phased out. Stick with the OAuth options to avoid issues down the road. Inboxy also supports multiple accounts under a single login, which is handy if you're managing warmup across several businesses or brands.

Configuring Your Warmup Schedule

Once your inbox is connected, Inboxy offers two setup paths: instant setup (no configuration needed, fine-tune later) or detailed setup where you control everything from the start. The detailed setup is worth exploring because it exposes all the dials you can turn.

The first configuration screen handles sending hours. You set your time zone, define which hours of the day emails go out, and choose which days of the week are active. Monday through Friday is the sensible default — you want your sending pattern to look like a real person's, not a bot hammering away 24/7.

There's also a "reply-to email" field, which lets you route replies to a different address. For most warmup scenarios, though, you'll want to leave this set to your sending address. Using a different reply-to during warmup could introduce signals that make the whole process less effective.

Setting Warmup Goals

The goals screen is where Inboxy starts to differentiate itself. You configure your starting daily email volume (between 20 and 90), set a daily increase rate (defaulting to 20%), and define what happens after the initial warmup completes.

Inboxy breaks the warmup into three distinct phases. First is the initial warmup, which gradually ramps up your sending volume. Next is an optional extended warmup phase that continues building your reputation. Finally — and this is the standout feature — there's a maintenance phase that keeps your inbox placement score (IPS) in the excellent range even when you take breaks from active sending.

That maintenance phase is genuinely useful. If you stop sending emails for a while, your deliverability can slip. Having Inboxy automatically pick up the slack and keep your reputation intact is a set-it-and-forget-it solution that most competing tools don't offer. You can target a specific IPS score (90 or above puts you in the "excellent" range) and get notified by email when each phase completes.

Fine-Tuning Rules and Engagement Signals

The rules configuration is the final and most nuanced step. This is where you tell Inboxy how to simulate realistic email engagement. Several key metrics come into play here.

First is the unspam rate — set at 100% by default and currently locked. This means every warmup email that lands in spam gets moved to the primary inbox, sending a strong signal to providers that your messages are wanted. Next is the reply rate, adjustable via a slider and defaulting to 50%. Half of your warmup emails getting responses is a solid indicator of legitimate communication.

Open rate is fixed at 100%, which makes sense during warmup — you want every signal pointing toward "this sender is real." The star rate (how many emails get starred or marked as important) defaults to 30%, though Inboxy recommends 40-80% during warmup and even higher during post-warmup when you're mixing in actual cold emails. The logic is sound: as you dilute warmup sends with real outreach, you want the engagement signals from the warmup emails to compensate and keep your overall metrics healthy.

The Inboxy Dashboard

Once everything is configured, the Inboxy dashboard gives you a clear overview of your warmup progress. You can see how many emails are queued, sent, opened, unspammed, replied to, and starred — all the metrics you configured in the rules section, now tracked in real time.

The dashboard also displays your Inbox Placement Score for both Microsoft and Google, which is exactly the data you need to gauge whether the warmup is working. There's both a grid view and a list view for managing multiple inboxes, plus quick access to pause sending, jump back into settings, reconnect your inbox, or remove it entirely.

Design-wise, the dashboard is functional but not exactly polished. The color palette leans heavily into autumn tones — think pumpkin spice rather than sleek SaaS. Some text elements are squished together, and the contrast could be better for quick scanning. But these are cosmetic issues. The data itself is comprehensive and well-organized, which is what actually matters when you're monitoring a warmup campaign.

How the Warmup Process Actually Works

Under the hood, Inboxy connects to your email server and sends messages from your address to a network of managed inboxes spread across different email service providers. Those managed inboxes then interact with your emails — opening them, replying, starring, and moving them out of spam — all according to the rules you configured.

This simulated engagement teaches email providers that your domain is legitimate and your messages are wanted. Over time, as your sending volume gradually increases and engagement stays high, your sender reputation improves. The emails themselves are generated using ChatGPT 3.5, which doesn't really matter — they just need to look like real messages to pass basic content checks.

Is this dishonest? Not really. You're not gaming the system to send spam. You're building the reputation you need so that your legitimate emails can actually reach people. You should still follow all spam laws and only send to people who want to hear from you. Warmup tools like Inboxy just make sure the infrastructure is ready when you are.

Holiday Scheduling

A small but thoughtful feature tucked behind a coffee cup icon in the upper right corner: holiday scheduling. You can add specific dates — like Christmas, Thanksgiving, or any days your business typically goes quiet — and Inboxy will pause sending on those days.

Holidays can be set as recurring annually, so you configure them once and they're handled every year. The idea is simple: real humans don't usually send work emails on major holidays, so pausing your warmup emails on those days makes the entire pattern look more authentic. It's a minor detail, but it's the kind of thoughtful touch that shows the team behind Inboxy understands the nuances of email deliverability.

Final Thoughts

Inboxy is the kind of tool that's hard to give a definitive verdict on after just one session — email warmup is inherently a weeks-to-months process. But the first impression is strong. The feature set is well thought out, from the three-phase warmup structure to the maintenance mode that keeps your reputation intact during quiet periods.

The setup process is intuitive even in detailed mode, and the granular control over engagement signals (reply rates, star rates, unspam behavior) gives you real flexibility. The dashboard provides exactly the metrics you need without unnecessary clutter. The main knocks are cosmetic: the color scheme could use a refresh, and a few UI elements feel cramped.

At $59 for a lifetime deal with inbox swapping included, the value proposition is compelling — especially if you're managing warmup for multiple clients or domains. Whether you're launching a new cold outreach campaign or reviving a dormant email list, Inboxy covers the fundamentals and adds a few smart extras that competing tools lack.

Watch the Full Video

Prefer watching to reading? Check out the full video on YouTube for a complete walkthrough with live demos and commentary.