I'm planning on receiving email/forwarding email using postfix, but sending email using sendgrid.
According to this tutorial, I need an MX record pointing to my machine - http://www.andreagrandi.it/2014/08/31/getting-started-with-digital-ocean-vps-configuring-dns-and-postfix-for-email-forwarding/
I've already set up sendgrid, and its working -> i sent a test email from email@example.com. I did this with no change to my DNS.
My question is, when I set up the MX for email forwarding, will sendgrid stop working?
From what I'm reading, I need an MX record saying sendgrid is a valid sender. But today, sendgrid is able to send, without me doing any DNS change.
I would "just try it" but its my first time with email, and the blacklists make me paranoid.
I've read other answers on mail setup, but I haven't seen one with a different setup for sending and receiving.