Mailbox verification infrastructure

If you saw mailjaguar.com in your mail server logs, this page explains why.

mailjaguar.com is the network identity used by VerifyBuddy, an email verification service. Businesses use it to remove addresses that no longer exist from their own contact lists, which lowers bounces and spam sent to dead mailboxes.

What our servers do

We open a short SMTP session and ask whether a single recipient address exists, then disconnect. No email is ever sent. We never issue the DATA command.

EHLO mail.mailjaguar.com
MAIL FROM:<verify@mailjaguar.com>
RCPT TO:<someone@your-domain.example>
QUIT

How we limit impact

Strict per-domain and per-IP rate limits, kept deliberately low.
We back off automatically when a server returns a policy, reputation or rate-limit response.
Results are cached, so the same address is not checked repeatedly.
Every sending IP has matching forward and reverse DNS, and is listed in this domain's SPF record.

Opt out or report a problem

To stop all verification requests to your domain, or to report anything that looks wrong, email abuse@mailjaguar.com (or postmaster@mailjaguar.com). Include your domain name and, if possible, a log line with the connecting IP and time. We add opted-out domains to a permanent suppression list.