I didn't down vote you; your comment adds to the discussion. The annoying SPF/DKIM additions to your DNS zone file are necessary for the basics of delivery to

I didn't down vote you; your comment adds to the discussion. The annoying SPF/DKIM additions to your DNS zone file are necessary for the basics of delivery to the inbox. Gmail now displays a scary red unlocked padlock for unsigned/unverified email. Running an SMTP server is indeed the way the internet was meant to handle email. However, the other tenants in your /25 CIDR block will ruin your sending IP address's reputation and you will face delivery to Spam and throttling unless you stay on top of blacklist removal requests. There are plenty of use cases for using your own SMTP server for sending, but I think the labor cost of doing so far exceeds the prices of Sparkpost, Postmark, Mailgun, Sendgrid, or hell, even Mailchimp.