Approved senders and blocked senders lists

Products

• Email Security.cloud

Issue/Introduction

Learn how to work with the approved and blocked senders lists in Email Security.cloud.

Resolution

Within Email Security.cloud, you can define a list of approved senders or blocked senders for your organization.

• Approved senders - An approved sender is identified by their IP address, domain name, or email address that you want to receive email from, even though they may be on the public or customer block list.
• Blocked senders - A blocked sender is an IP address, domain name, or email address that you want to block emails from.

 

You can define approved and blocked senders lists at the following levels:

• Global level
• Group level
• User level

 

For example:

• You can enable users to manage their own lists and manage those of others yourself.
• You can define a user's lists initially and the individual user can manage them in Email Quarantine thereafter.
• You cannot define approved senders and blocked senders lists at the domain level. You define approved and blocked senders lists in the following ways:
  • Manually add entries to the list in the portal.
  • Download the existing list, edit it locally, and upload the revised list back to the portal.

 

The portal accepts entries in the following formats:

• IP address with a wildcard or CIDR notation (/1 to /32)
• Domain name: subdomains are included by default, and wildcards (*) not accepted.
• Email address: wildcards (*) are not accepted.

 

The list strictly applies to the envelope sender email address, also designated as RFC5321.Mail From.

Note: "X-Env-Sender" is inserted into the header of the email to assist administrators. If you enter a domain in your approved or blocked senders list, it includes all of its sub-domains automatically. For example, if you add mydomain.com as an approved sender, it will also apply to sub.mydomain.com.

Entry limitations

Each entry is subject to validation rules to work properly. For a complete list, see our Validation rules for Anti-Spam approved and blocked senders lists article.

• Global and User approved and blocked senders lists can contain up to 3000 entries each.
• Group-approved and blocked senders lists can contain up to 150 entries each.
• You cannot add a user who is on the exclusion list as an approved or blocked sender.

Risks

Do not put your domain name in your own approved senders list. By including your own domain name, you open the organization up to a security exploit.

This may occur because spammers sometimes spoof the sending email address to match the target email domain (you) in an attempt to bypass Anti-Spam scanning. Instead, include your partners' sending IP addresses.

Additional Information

To learn how each scanner flags an email, see About Anti-Spam detection settings and actions. This can be used effectively to only allow approved senders for a specific scanner rather than a complete bypass.