Mailreach
Mailreach is not a sending platform; it is a warmup and deliverability testing tool. It warms mailboxes by sending emails between accounts, simulating real engagement, and gradually increasing volume. It also tests inbox placement (inbox vs. spam vs. promotions tab) across Gmail, Outlook, and other providers. Teams use Mailreach alongside Smartlead or Instantly to ensure deliverability before launching campaigns.
Official site ↗Why it ranks here
Mailreach is the best dedicated warmup tool. The warmup algorithm is transparent (you can tune reply rates, sending cadence, and folder distribution), and the inbox placement testing gives real signals before you burn your sender reputation.
Where it sits
Mailreach ranks as strong because it solves one problem better than any sending platform: mailbox warmup. It does not send cold emails (you need another tool for that), but it ensures your mailboxes are ready. Most serious teams use Mailreach in addition to Smartlead or Instantly.
How GTM Engineering teams use it
Engineers connect new mailboxes to Mailreach before connecting them to a sending platform. Mailreach warms the mailbox over 2-4 weeks, sending emails to other Mailreach users and simulating opens, clicks, and replies. Before launching a campaign, they run an inbox placement test to confirm the mailbox lands in the inbox (not spam). If placement is poor, they adjust domain settings or wait longer before sending.
In-depth notes
Pricing is per-mailbox monthly subscription. The warmup period is weeks (you cannot skip this without risking deliverability). The inbox placement testing is accurate and gives results across multiple providers (Gmail, Outlook, Yahoo). The main downside is cost: warming multiple mailboxes adds up. Best for teams that cannot afford deliverability failures.
Best for
Teams that need reliable mailbox warmup and inbox placement testing before launching campaigns.
Avoid if
You are on a tight budget or only sending a few hundred emails per month.
The rest of Sending & deliverability
Smartlead Leader High-volume cold email with mailbox rotation and inbox monitoring. #2 
Instantly Leader Affordable cold email sending with built-in mailbox warmup. #3 
lemlist Strong Cold email with strong personalization (video, images, dynamic landing pages). #4 
Salesforge Strong AI-powered cold email with built-in mailbox and domain provisioning. #5 
QuickMail Strong Simple cold email sending with inbox rotation and basic analytics. #7 
Woodpecker Situational Cold email automation with strong CRM integration and follow-up logic. #8 
GlockApps Situational Inbox placement testing across Gmail, Outlook, Yahoo, and other providers. #9 
Warmup Inbox Situational Automated mailbox warmup by simulating engagement across a network. #10 
Warmy.io Niche Mailbox warmup with deliverability monitoring and spam testing. #11 
Amazon SES Niche Raw email sending infrastructure (SMTP/API) for custom-built outbound systems. #12 
Infraforge Niche Automated domain and mailbox provisioning for cold email infrastructure. Learning guide
Setup
Connect new mailboxes to Mailreach before connecting them to your sending platform. Configure warmup settings (reply rate, sending cadence, folder distribution) and start the warmup process. Mailreach sends emails to other users in the network and simulates realistic engagement.
First thing to build
After 2-3 weeks of warmup, run an inbox placement test by sending a test email to a Mailreach-provided address. Review the placement report (inbox vs spam vs promotions) across Gmail, Outlook, and Yahoo. If placement is good (inbox rate above 90 percent), connect the mailbox to your sending platform and launch campaigns.
What actually matters
- Warmup duration: 2-4 weeks minimum, longer for mailboxes with no prior sending history
- Tuning options: adjust reply rate (30-50 percent), daily send volume (gradual ramp from 5 to 40), and folder distribution to simulate real behavior
- Inbox placement testing: test before launching campaigns and after any deliverability issues to diagnose problems
- Cost management: warmup is per-mailbox subscription, so budget increases with mailbox count
Watch out
Skipping warmup or cutting it short will result in poor deliverability that takes weeks to recover.