All these old RFCs

For p25.dev I was researching a feature. Customers who don&rsquo;t have a static IP address, or sit behind a firewall they can&rsquo;t control, should be able to use p25.dev&rsquo;s backup MX too. I try to be standards compliant as much as possible, so I researched existing solutions. In 1999, the ON-DEMAND MAIL RELAY (ODMR) RFC 2645 was proposed. It allows an SMTP client to tell the server…