Overview

At times, the IP address from which you send emails may be marked as spam sender or blacklisted by email service providers (e.g., Gmail, Yahoo, Yandex, etc.). The following error may appear in the logs:

Our system has detected an unusual rate of unsolicited mail originating from your IP address

Prerequisites

• Access to Kerio Connect Webadmin
• Access to Domain Records configuration

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Diagnosis

Depending on the email traffic you're sending (bulk or marketing emails, etc), the Kerio Connect Public IP address may become blacklisted or marked as a Spammer host in the Known Spam Relay Blocking systems (like SORBS).

From time to time, the user accounts may become compromised, which generates big traffic of spoofed emails, which leads to a decrease in Domain and IP address reputation.

The sender score is in your own control and responsibility and in most cases, not an issue caused by the Kerio Connect configuration.

To improve your emails' reputation and prevent messages being marked as spam by other vendors, it's recommended to follow the process below.

Solution

1. Configure the SPF record.
   
   Note: There are multiple ways to create an SPF record. It is recommended to include the IP address of your server to the SPF record.
   We suggest using the following format (replace 1.1.1.1 with your real IP address):
   v=spf1 mx ip1.1.1.1 ~all
   
   
2. Configure DKIM and DMARC records.
   If you are not sure how to create such records, please contact your Domain Registrar.

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Confirmation

Emails should not be rejected by other providers any more, while domain reputation should increase.

Note: some external email providers have delisting periods, after which the email Domain and IP address becomes clean and is removed from the Blacklist. For more information, please contact the Blacklisting Authority (SORBS, Spamhaus, etc).

 

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