By default, the application does not integrate an unsubscription link within the emails sent via the SMTP relay. However, there is a specific feature which enables you to do this. This option can be activated on-demand.
When this feature is activated, the user must add the usual unsubscription variable ($unsubUrl$) to the design, then the platform will replace the variable by a link when the email is being processed.
To get more information and activate this feature, please speak to your Splio contact.