people in my partner organization would like to send email from my domain name
like Abc.com is my domain and xyz.com is my partner domain. they want to send email as firstname.lastname@example.org
and i dont want to allow their Public IP to whitelisted in ABC.com. instead i would go SPF or DKIM.
Since SPF and DKIM is new to me. i am interested to implement either SPF or DKIM . could you please assist me on this