SPF
To allow Critsend to send emails on your behalf, you will have to add them to your SPF record. The SPF mechanism used by Critsend is shown below.
include:messaging-master.com
DKIM
Critsend support DKIM as well. Please click on the button below to access their documentation and instructions on SPF and DKIM.
Create a free OnDMARC account to test your configuration.