Relevant Product: Signature Manager Exchange Edition
Users are receiving spam emails from senders that have been spoofed. The email looks more authentic when the Exclaimer Signature Manager Exchange Edition appends the sender’s signature to the email.
The issue occurs because the email domain specified as the sender in the email received has been spoofed.
The Exclaimer Signature Manager Exchange Edition appends a signature to the spoofed email because the sender and/or recipient in the email match the conditions specified for the relevant signature policy.
Exclaimer processes all emails submitted to the server where it is installed - this includes emails sent internally, externally, as well as inbound.
Signature Manager Exchange Edition cannot identify emails from senders that have been spoofed - nor is it possible to turn off the direction of mail flow that Exclaimer processes.
It will help if you use an SPF record, as only senders from authorized IP addresses are permitted to send emails from the domain.
While this will not stop spoofing attacks that originate from inside your domain, this will stop external attacks.
If you do not know how to create or update your SPF record, we recommend that you contact your hosting service provider or whoever is responsible for hosting within your organization.