Postgrey currently blocking Sendgrid outbound client source

More sites are using Sendgrid as their SMTP service of choice. Without allow listing their `outbound-mail.sendgrid.net` subdomain (which they use for outbound SMTP) most emails coming from Sendgrid will be blocked by default. I noticed that `mailgun.net` is already in the default client allow list. How would we feel about adding sendgrid as well? 