Outbound Filtering

Much like for our Inbound Filtering, Outbound Filtering has its own set of parameters that allow you to personalize how the service works.

Administrators can manage Outbound Filtering preferences under:
My Organization → Parameters → Outbound Filtering

This article applies to Administrator accounts - Quarantine Administrator accounts can view this information but cannot edit the parameters

Please note that any changes made under the Parameters tab can take up to 5 minutes to take effect.

Important Considerations Outbound Filtering Parameters
Configuration Deconfiguration

Important Considerations

  1. Office 365 and Microsoft Exchange are currently supported by our Outbound Filtering. For configuration instructions, please see the Related Articles
  2. Google Apps (G Suite) hosting is not supported by our Outbound Filtering. This is due to technical limitations by Google (which does not support SMTP-Auth).
  3. If you have an SPF record on any of your domains using our Outbound Filtering, you must add the following entry to your SPF record: a:outbound.zerospam.ca . For more information about SPF records, please consult the Related Articles.


To enable outbound configuration:

Parameters → Outbound Filtering → Configuration

By clicking the create button, Cumulus will automatically configure outbound filtering for the account with the correct identities based on your current transport.

Configuring Outbound Filtering will modify billing. Please contact us if you have any questions.

The field Outbound mail relay is your designated relay.


We don't want our outbound filters being used as open relays. For that reason, we identify outbound transactions on two levels. The first level is by authenticating the sending server. The second level is by authenticating the sending domain.
Once an identity-type is chosen, you also need to select a Filtering Policy which will apply to all emails using that identity.

Sending Server

You can manage which forms of server authentication are configured under:

My Organization → Parameters → Outbound Filtering → Identification

This will let you edit an existing identity or add a new one.

There are 4 methods of authenticating the sending server:

  1. IP address: adds the IP addresses of the servers you will use to send emails through our filters. Can accept IP addresses or CIDR blocks. Addresses must be unique to each customer.
  2. SMTP-Auth: Cumulus will generate a username and password. These must then be used by your server whenever it connects to our Outbound filters to send emails.
  3. Office 365: adds all Office 365 as authorized servers for Outbound Filtering.
  4. Shared IP: can only be used by partners for their clients. Allows a partner to assign the same IP addresses for multiple client accounts.

This will let us know that the servers are yours and will let us apply the correct Outbound Filtering parameters. 

If a non-authorized server attempts to send mail via our filters, it will be blocked.

Sending Domains

You can manage which domains are added to outbound filtering under:

My Organization → Parameters → Outbound Filtering → Filtering Policy Groups → Domains.

By default, all inbound domains are added to the outbound filtering.

If a domain isn't in Cumulus our filters will not accept emails for it. 

Outbound Filtering Parameters

If Outbound Filtering is configured, you will have access to the Outbound Filtering parameters under :
These parameters allow you to personalize which emails are blocked or pass through our filters. Collectively, all the filtering parameters are known as a Filtering Policy.
Recipient Whitelist Enter an address or a domain. All anti-spam verifications are skipped for that recipient except Banned File verifications and anti-viral verifications.
Recipient Blacklist Enter an address or a domain. All emails sent to this recipient will automatically be rejected by our filters.
Sender Whitelist Enter an address or a domain. All anti-spam verifications are skipped for that sender except Banned File verifications and anti-viral verifications.

The Outbound Filtering parameters also allow you to specify what types of files are allowed to be sent. You can learn more about our banned file scanning by checking out the Related Articles


Outbound filtering can be deactivated manually.

Please note, the deconfiguration will be done in the following days. You will be warned if we still receive traffic on the outbound SMTP relay to avoid the loss of emails.

Navigate to the configuration tab under Parameters → Outbound Filtering → Configuration and click the link Delete outbound configuration on the right side of the page.

Do not hesitate to contact us if you need assistance!