Kayako IP Address is Blocklisted, error "This message was rejected by the recipient's mail server"

Overview

At times, you may observe or see that Kayako's sending IP address is being blocked by a server which causes your email message to be rejected and not being sent. When trying to reply to a conversation in Kayako, you may receive a bounce-back message like the one in the image below, with an error message saying "This message was rejected by the recipient's mail server at <date and time> with the error "550" JunkMail rejected"

Solution

An Internet Protocol (IP) address is a unique numerical address that defines a location. At Kayako, we are using dedicated IP addresses for sending email messages. Since we are the only ones sending emails over these IPs, Kayako customers' sending practices determine our "sender reputation" associated with these IPs. This reputation would often become the basis of how servers treat our messages or emails.

Blocks occur when a mail server IP address is added to a blocklist (or blacklist) primarily because of sending violations such as the IP or domain was used by spammers to send bulk or spam emails. Blocks may also take place if the message content is flagged by a filter on the receiving server.

If you receive the error message in Kayako, it will include the error code in it which contains the reason for the blocked as well as the associated web address where you can view the entire information. Some servers would typically remove the block automatically after 24 to 48 hours.

Check to verify if the IP is one of our sending IP addresses. The following is the list of IP addresses that Kayako uses for outgoing emails.

Trial Kayako instances:

• 52.201.201.236

Paid Kayako instances:

• 168.245.111.175
• 149.72.140.4
• 168.245.101.125
• 167.89.67.6
• 167.89.49.25
• 167.89.42.72
• 192.254.121.229
• 167.89.80.79
• 167.89.80.78
• 167.89.80.77
• 167.89.80.213
• 167.89.102.105
• 167.89.102.104
• 167.89.1.155
• 167.89.0.10
• 149.72.51.116

If a mail server blocks one of these IP addresses and you are still unable to send an email after 24 to 48 hours, then submit a request to de-list the IP address. 

Resolution steps

1. Click the Submit a ticket button at the top or at the bottom of this page or click this submit a request link. If you already have an open ticket for this issue, please proceed to step 2.
2. In your ticket, provide the details of the issue including a screenshot of the error if there's any.
   • Write a short description of the issue and include information such as:
     • The IP address listed in the error message.
     • The error code listed in the error message.
     • The name of the mail server that is blocking the email or the URL provided in the error message.
   • A reproduction video is preferred if available. This will help us expedite the solution should there be a need to investigate the issue further.
   • If you are allowing support to impersonate your account for troubleshooting purposes, please include an explicit approval on the ticket along with the email address of your Kayako administrator account.

The support team will send this information to a specific team that will contact the email servers and requests to unblocked our IP addresses.

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Confirmation

Once we get the IP address unblocked, you will receive a confirmation email from the support team and you should be able to send any emails or respond to any conversations without the error message.

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