To authorize Send13 to send emails on your behalf you will have to include it in your SPF record. The SPF record mechanism used for Send13 is shown below.
For more information on SPF set up for Send13 please click on the button below.
To enable DKIM you will have to login to your Send13 client area. Please click on the button below for more information.
Create a free OnDMARC account to test your configuration.