Restrict SMTP traffic in Email security cloud

Products

• Email Security.cloud

Issue/Introduction

The article clarifies why the recommendation to Restrict SMTP traffic in ESS is important

Environment

Email Security.cloud

 

Cause

We recommend that you lock down port 25 SMTP traffic to and from your Internet gateway to the following

IP ranges

Resolution

Locking down port 25 prevents spam and viruses being sent directly to or from your mail server. It also enables balancing the traffic across the infrastructure if Internet conditions require it. For example, during mass mailer outbreaks, dictionary attacks, and denial-of-service attacks.

Warning: If you do not accept email from these IP ranges, there is a risk of partial email failure.