Added note to #3 to clarify MX Records cannot point to a CNAME or Alias but there is a work around discussed in this commit where you can create a second A record for subdomain.domain.tld and refer it to the IP address of your incoming mail server.

Added one additional bullet point under "Troubleshooting" section based on my experience implementing emailwiz with a New Top-level Domain (NTLD) and sending emails to colleagues at large F500 companies.

documentation changes

Literally added one letter

Technically Postfix is responsible for sending *and* receiving mail between *your server and other SMTP servers* (Mail Transfer Agents). Dovecot is only so you can view your mail in email clients on your computer instead of server, which is not really *receiving*. You can have a perfectly functional email system with no IMAP/POP server at all, you'd just have to read your email over SSH or whatever

Typos + other tiny corrections, is it "honestly have" or "honestly don't have" preference towards vultr? Tried to guess...