SPF
To authorize ProtonMail to send emails on your behalf you will have to include it in your SPF record. The SPF record mechanism used by ProtonMail is shown below.
include:_spf.protonmail.ch
DKIM
ProtonMail supports DKIM signing for your custom domain. For more information on SPF and DKIM please click on the button below.
Create a free OnDMARC account to test your configuration.