alt Hacker NewsI mind email for a number of small orgs (<1000 recipients each). There are so many SPF and DKIM failures from senders who you'd think would know better (Fortune 100-type companies). I don't want complaints from users missing messages so I end up disregarding failures even when published policy says to do otherwise.
I take the opposite approach, I refuse to whitelist domains. When someone internal complains I send a notice to their contact on the other end (CCing the internal recipient) saying their email is misconfigured and ask them to put me in touch with their IT department to help them fix it. I use a script to do some DNS lookups and write the email for me. I have about a 50% success rate getting them to fix it.