Mailwarm
Warmbox.ai
MailReach.co
Warmup Inbox
Warmy.io
Folderly
Lemwarm by Lemlist
lemlist
Sortfully
Sanebox
Clean Email
Mailstrom
Mailwarm is an automated email warmup and deliverability platform designed to help businesses keep their emails out of spam folders and consistently reach the inbox.
Since 2020, Mailwarm has helped founders, sales teams, marketers, and agencies improve email deliverability, build strong sender reputation, and scale cold email outreach safely. We focus on the real fundamentals of deliverability: trust, consistency, and genuine engagement.
Mailwarm automatically warms up new domains, inboxes, and SMTP servers by generating natural interactions between real email accounts. This process protects your reputation, prevents spam filtering, and improves inbox placement across major providers including Gmail, Outlook, Microsoft 365, and Yahoo.
Key Features: - Automated email warmup for Gmail, Outlook, and Microsoft 365 - Multi-provider warmup for realistic sender reputation building - Spam score tracking to measure inbox vs spam performance - Bounce prevention and verification systems - SMTP, domain, and mailbox warmup - Easy one-click Outlook & Office365 connection - Guided SMTP setup and deliverability monitoring - Stable warmup with auto-recovery from connection issues - Team and agency management with flexible plans
Email warmup is not a hack, it’s a process. Mailwarm was built to do it properly, using real engagement signals to help your emails earn long-term trust with mailbox providers.
Whether you’re launching new outreach campaigns, onboarding new sales reps, or managing multiple client accounts, Mailwarm helps you send emails with confidence and achieve better inbox placement instead of landing in spam.
Mailwarm is not just an email warmup tool. Every plan includes an email deliverability expert who works with you to set up your infrastructure, monitor your performance, and fix issues that impact your inbox placement. Most tools show you data. Mailwarm helps you improve results.
Sortfully is an automatic filing service for Outlook and Microsoft 365. It moves each message into an Inbox subfolder, or tags it with a coloured category, based on the organisation that sent it. By default a message is only filed once you have read it, so new mail still lands in front of you and nothing disappears unseen. If you prefer, filing can happen instantly on delivery instead.
There is no AI in Sortfully. No model, no classifier, no LLM, and your mail is never sent to any AI service. Filing runs on deterministic rules you can read and edit: the sender's domain, your exact-match overrides, then Public Suffix List normalisation, so notifications.slack.com and hello@slack.com both land in one Slack folder, and .co.uk domains get correct names. You can group several domains into one folder, pin a domain to a folder you already have, exclude senders entirely, and choose move-or-tag per organisation. Every action is reversible.
Privacy is structural, not a promise. Sortfully never reads message bodies or attachments: the one code path allowed to call Microsoft Graph message endpoints uses a strict metadata field allow-list, and a CI gate fails the build if a content field ever appears. An optional detailed audit log records the subject line so you can see exactly what was filed; you can switch it off. Sortfully connects through delegated Microsoft Graph permissions only (Mail.ReadWrite, Mail.ReadWrite.Shared, MailboxSettings.Read), is a verified Microsoft publisher, and reads your existing inbox rules without ever modifying them. Tokens are encrypted at rest and you can disconnect at any time.
Optionally, a chunked, throttle-safe backlog cleanup sorts the mail you already have, with protected folders and a leave-recent-mail window so nothing current is touched.
Sortfully is built for Microsoft 365 first: individual mailboxes, shared mailboxes, and a Business plan with team management for firms. It is operated by a UK company, hosted in the EU.
Mailwarm SortfullyMailwarm's answer
Mailwarm is an email warmup and deliverability platform built by a Y Combinator and Station F startup.
Since 2020, we’ve worked with many types of companies: SaaS startups, recruitment agencies, e-commerce brands, and sales teams; to help them improve inbox placement safely.
Mailwarm is unique because it offers: - Real multi-provider warmup (Gmail, Outlook, Microsoft 365, Yahoo)
Clear and real spam score tracking
Built-in bounce prevention
Easy setup and stable automation
Our focus is simple: help businesses keep emails out of spam and land in the inbox.
Sortfully's answer:
Sortfully contains no AI at all. Filing runs on deterministic rules you can read and edit: the sender's domain, your overrides, then Public Suffix List normalisation. And the privacy guarantee is structural rather than promised: the one code path allowed to call Microsoft Graph message endpoints uses a strict metadata allow-list, and a CI gate fails the build if a content field ever appears. Message bodies and attachments are never read.
Mailwarm's answer
Mailwarm delivers real, measurable results instead of risky shortcuts.
Users choose Mailwarm because it provides: - Automated email warmup that protects sender reputation
Multi-provider engagement for realistic signals
Spam score to track deliverability progress
One-click Outlook and Office365 connection
Reliable campaigns with auto-recovery
It’s an easy, transparent, and professional way to improve email deliverability.
Sortfully's answer:
Most email organisers ask you to trust them: an AI classifier scores your mail and a privacy policy promises restraint. Sortfully is built so you don't have to take its word for it. It cannot read message bodies or attachments; the restriction is a code-level allow-list backed by a CI gate that fails the build, and filing runs on deterministic rules you can read and override. It is also the only one of its kind built for Outlook and Microsoft 365 first: delegated Microsoft Graph permissions from a verified Microsoft publisher, shared mailbox support, and read-only respect for your existing inbox rules, where SaneBox, Clean Email and Mailstrom treat Outlook as a second platform. And it behaves differently: mail is filed by sender organisation, so every alias and subdomain lands in one folder, and by default only after you have read it, so nothing disappears unseen and everything can be undone.
Mailwarm's answer
Mailwarm is for anyone who depends on email outreach:
Sales teams sending cold emails
Founders and startups launching new domains
Marketing agencies
Recruiters and staffing firms
Growth and outbound teams
If inbox placement matters to your business, Mailwarm is built for you.
Sortfully's answer:
Businesses and normal consumers can both benefit from Sortfully. Businesses on Microsoft 365, mainly professional services firms of 10 to 200 mailboxes (accountants, solicitors, surveyors, architects) and the IT admins or MSPs who manage their tenants. It also suits compliance-conscious firms that have decided against AI email tools, and individual Outlook power users.
Mailwarm's answer
Mailwarm started as a real problem we faced ourselves.
We were two founders working at Station F in Paris, the largest startup incubator in Europe, trying to sell our own products. Every time we launched outreach campaigns, our emails kept landing in spam.
To solve this, we built an internal email warmup system for our personal use. After deep research into email deliverability, we created a stronger, more reliable solution.
Other startups in the incubator quickly asked to use it too; so we turned it into a real product.
After launching publicly, Mailwarm became #1 Product of the Day on ProductHunt and was accepted into Y Combinator, the world’s most prestigious startup accelerator.
Since then, Mailwarm has grown into a trusted platform used by thousands of companies to improve inbox placement and email deliverability.
Sortfully's answer:
Sortfully was built by a UK founder who watched Outlook rules fail at scale: Exchange caps rules at 256 KB, one rule per sender domain does not scale, and rules only run while Outlook is open. The alternatives all wanted AI access to mail content, which is exactly what regulated firms cannot accept. So Sortfully does the opposite: deterministic filing by sender organisation, with a code-enforced guarantee that message bodies and attachments are never read. It launched in August 2026, operated by a UK company with EU hosting.
Mailwarm's answer
Mailwarm is a secure cloud-based SaaS platform built on:
SMTP and IMAP email protocols
Advanced verification systems
Multi-provider infrastructure
Real-time analytics and monitoring
Reliable automation engines
These technologies ensure stable, continuous email warmup.
Sortfully's answer:
Laravel (PHP), PostgreSQL and Redis on the backend; React with TypeScript and Inertia on the frontend; the Microsoft Graph API with delegated permissions for all mailbox access. Hosted in the EU.
Mailwarm's answer
As a Y Combinator and Station F startup, Mailwarm works with:
Tech startups and SaaS companies
Recruitment and staffing agencies
Real Estate Agencies
B2B marketing agencies
E-commerce brands
Sales and outbound teams
Freelancers and consultants
From France to global markets, hundreds of organizations trust Mailwarm to improve email deliverability and inbox placement.
I decided to try Mailwarm after having consistent issues with my emails landing in spam folders. At the beginning, I wasn’t fully sure what to expect, but the onboarding process was simple enough to get me started quickly. After running it for a while, I began to notice a steady improvement in my email deliverability. More of my messages started reaching the inbox instead of getting filtered out, which really helped with my outreach efforts. Overall, it’s been a reliable experience. It may not be perfect, but it definitely does what it’s supposed to do if you give it time.
I started using Mailwarm because I was struggling with my emails going straight to spam, especially for outreach. At first, I wasn’t expecting much, but after a couple of weeks, I actually started noticing a difference. The setup was pretty simple, and once everything was connected, it just kept running in the background without me needing to constantly check it. That’s something I really appreciated.
Overall, I’d say it’s a reliable tool if you’re serious about improving email deliverability without overcomplicating the process.
I have been using Mailwarm to warm up email accounts and improve overall deliverability for my outreach campaigns. The setup process was very simple and everything runs automatically without requiring constant monitoring. Since using the tool, I’ve seen a clear improvement in inbox placement and fewer emails landing in spam. It’s a reliable and effective solution for anyone doing cold email or managing multiple inboxes.
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