MailChannels SMTP Relay

MailChannels SMTP Relay is a hosted email relay service with powerful outbound spam filtering features. It is designed to eliminate IP blacklisting problems related to compromised end-user accounts and spam.

Getting Started

MailChannels SMTP Relay allows you to ensure a reliable SMTP service for your users with minimal maintenance. A web interface searches billions of email logs in seconds, allowing you to track down and diagnose email delivery problems. MailChannels SMTP Relay outsources the problem of blacklisting and abuse management by sending outbound SMTP traffic through MailChannels IP addresses.

With MailChannels SMTP Relay, you only pay for what you use. For $49.99 billed monthly, the Starter plan includes 40,000 outbound messages per month and there’s no long-term commitment. MailChannels SMTP Relay provides email administrators an easy way to protect their email sending reputation so your IP addresses are never blocked by blacklists (Spamhaus, SpamCop, UCEPROTECT®, and more).

Designed for:

  • Shared Hosting Providers
  • Enterprise


MailChannels SMTP Relay painlessly resolves IP blacklisting issues.
  • Uses standard SMTP authentication; supported by almost every mail server.
  • Artificial intelligence figures out who sent each message, tracking sender behavior to detect and limit abuse.
  • ResponseAnalytics™ technology understands rejection messages from receivers, helping to identify compromised sender accounts and improve deliverability.
  • Automatically avoids blacklisting by pre-sorting outgoing email traffic into different risk categories and delivering out of hundreds of constantly monitored IP addresses.
  • Receive alerts in real-time whenever a user in your network is compromised.
  • NEW! Use webhooks to automate shutdown of compromised accounts.
  • Search through all your outgoing message logs using a simple yet powerful log search interface.
  • Set up management accounts with different levels of access.
  • Billed by the message with no hidden costs. Never pay for capacity you didn’t use.
  • Large accounts receive a dedicated Account Manager who will work with you to reduce abuse levels and lower your costs.
  • Transparently capture and redirect SMTP traffic in real-time to sinkholes.

How It Works

MailChannels SMTP Relay analyzes all outbound emails to detect spam and shutdown compromised accounts.

To use MailChannels SMTP Relay
  • Smart host your mail server to ours.
  • Your mail server inserts the identity of the user who created each message in the form of X-headers. This information is used to track users and identify accounts that are spamming.
  • Get reliable email delivery instantly. We manage the reputation of all users sending through our system very carefully.
Sender Authentication
  • By inserting “X-AuthUser” header, your mail server tells MailChannels SMTP Relay which user account is responsible for each message. This is a critical step for isolating the compromised accounts and ensuring successful results.
  • Setup instructions available for: Postfix, SendMail, cPanel, Exim, SmarterMail (Version 11+), PHPMail, and IceWarp.
Mail server not listed?Don’t worry — most mail servers have smart host setup instructions in your mail server’s documentation.

Why It Works

Your mail server sends email on behalf of many different kinds of email senders, including:
  • End users,
  • Applications and scripts,
  • Operating systems processes, and
  • Third parties via email forwarding.
Any type of sender may send spam, so the key to ensuring receivers trust email from your server is to block or slow down senders who are behaving like spammers. Blocking spam from every type of sender is a challenge, because each type behaves differently and has different needs. One of the first things we do within MailChannels SMTP Relay when we receive a message from you is to figure out what type of sender originated the message. Was it forwarded? Did a PHP script generate it? Or was an end user responsible for the message? Once we know what type of sender is responsible, we determine whether the content of the message is suspicious. And then we look at the sender’s history to determine:
  • Whether that sender’s messages have been rejected by receiving systems
  • Whether anyone has complained about the sender
  • Whether our own spam filters have seen any spam from the sender recently
  • And dozens of other factors.
Messages that contain obvious spam content are blocked. And senders whose behavior is suspicious are either temporarily or permanently blocked. Everything else is delivered through one of several IP address pools, which group similar types of senders together to achieve the best possible email delivery outcome for each group. Doing all of this at a large scale is an enormous challenge, which has taken us over seven years to develop.

Service Highlights

SecureMailChannels SMTP Relay is the only email deliverability platform that allows you to send spam through our system. Sophisticated outbound spam filtering technology cleans your outgoing SMTP traffic and ensures your customers always get reliable email delivery.
AutomateMailChannels SMTP Relay lets you eliminate blacklisting issues by outsourcing abuse management to MailChannels experts. By sending your SMTP traffic through MailChannels, you can solve blacklisting within minutes, not weeks.
InsightA web console allows you to easily monitor your sending activity and search logs to track down email delivery problems.
  • Whether that sender’s messages have been rejected by receiving systems
  • Whether anyone has complained about the sender
  • Whether our own spam filters have seen any spam from the sender recently
  • And dozens of other factors.
ScalabilityMailChannels SMTP Relay automatically scales to any volume requirement. MailChannels SMTP Relay uses Amazon Web Services and follows best practices for scalability and redundancy to ensure 99.95% service availability.
Designed for use with any mail serverSmart host your mail server over to ours and avoid the hassles of licensing, installing, and operating a third-party technology. Deploy within 5 minutes.
Sign up for MailChannels SMTP Relay From $49.99/month – month-to-month, no commitment.
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