Introduction

There are some times when users try to send the emails from their mail server to an external domain user faces an error that prohibits the user from connecting, and email cannot be delivered. The sender will receive a non-delivery Receipt with the following SMTP error:

554 5.7.1: You are not allowed to connect

Procedure

The error occurs mainly because of the Sender's IP or domain added to the blacklist. Some of the causes for an IP to be blacklisted are as follows:

• Sending an email to a list of recipients where the email's contents suggested it was spam raises the chance of being rejected while sending email from that email address.
• Sending bulk emails and engaging in email marketing or email newsletter distribution may make the sender more vulnerable to spam filters, increasing the chance of being blacklisted.
• If spam mail is sent automatically from the sender's email address by hackers or after being infected by a virus, it will raise the chance of adding the email address to the blacklist.

You will first want to review your server for any misconfigurations. The following article can provide some additional infomration on some configurations.  

Checklist for Emails going to Spam

After you verified that there is no problem on your server and there are no emails that are sending spam from the server, you should reach out to the server admin of the email you are sending to clear your IP from not being able to send an email. 

The following link has a composed listing of a few standard blacklisting reporting listings that you may request delisting. However, most of the time, the bounce-back message typically contains what listing you are registered on. 

Procedure to Remove Blacklist

Please note, cPanel LLC does not have the ability to provide assistance with clearing IPs or domains off of a blacklist. This task would need to be performed either by your system administrator or hosting provider if they provide assistance in these matters.