Blocking port 25

Introduction

If your private server is sending too much unsolicited mail, it is important to take action to preserve the reputation of your IP address and our network. This is because ISPs and email providers take into account the "cleanliness" of IP addresses that attempt to deliver mail to their subscribers. The more spam your server sends, the more the reputation of your IP address will drop, which may have serious repercussions on your business: for example, your correspondents will not receive your emails at all, or they will immediately end up in their "Junk Mail" box.

As a hosting company, we have an obligation to act in the interest of the network and all our hosted customers. As such, we must adopt a strict policy of eradicating spam from our network

In which cases we intervene

Our action is triggered mainly on the basis of complaints we receive and the interaction of users of email providers whose statistics are available to us. For example, when more than 90% of users consider that your mails are spam and/or when your server relays misleading and fraudulent mails (Phishing...). The information that we exploit is reliable and leaves no doubt about the abusive character of the use of the connections SMTP by your server.

How we intervene

If your server is sending too much spam, we will block port 25 in output which implies that your server will not be able to send mails to the outside, but will still be able to receive them. We will immediately notify you of our action by opening a ticket explaining the situation, as well as an example of mail that has been sent since your server.

We will unblock port 25 once you have identified and corrected the problem.

What you need to do

You should contact your webmaster to secure your server and stop abusive mailings. If these emails are sent without your knowledge, it is very likely that one of your sites is being exploited (contact form...) and that a security flaw needs to be corrected: this is very common with the use of CMS such as Joomla, WordPress, etc.

Your server may also be compromised, for example if you do not regularly update the system and Parallels Plesk Panel. In this case, contact your system administrator, or our support if you have .

If you do not have a outsourcing contract for your private server, we can possibly assist you in your steps by proposing you an intervention service aiming at securing your server and trying to identify the security flaw.

Updated on 12 April 2022

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