Mailnitrix address checks

If you found mx1.mailnitrix-verify.com or 147.135.110.81 in your mail server's logs, this page explains what it was.

What this server does

Mailnitrix is an email outreach platform. Before a customer emails a business contact for the first time, this server asks the contact's mail server whether the address exists. That way, emails to addresses that no longer exist aren't sent and don't bounce.

What a check looks like

It's an ordinary SMTP conversation that stops before any message is sent:

EHLO mx1.mailnitrix-verify.com
MAIL FROM:<check@mailnitrix-verify.com>
RCPT TO:<someone@your-domain>
QUIT

There's no DATA command, so nothing is delivered to anyone. This IP never sends email.

How much traffic to expect

• One connection at a time to each mail server, with a few addresses at most per connection.
• Answers are reused for weeks, so the same address is rarely checked twice.
• "Try again later" replies are respected, and checks to a server that refuses them pause for hours.

Stop checks for your domain

Email abuse@mailnitrix-verify.com with the domain, and it will be added to a list of domains that are never checked. You can also reach postmaster@mailnitrix-verify.com.