I setup and have been running an email server for around 20 domains for over a decade. There have been no issues delivering to Gmail or Outlook, AOL, or Hotmai

I setup and have been running an email server for around 20 domains for over a decade. There have been no issues delivering to Gmail or Outlook, AOL, or Hotmail. There was some work I did initiallity to remove our IP addresses from blackhole lists, which had resulted from whatever the prior owners of the addresses had done. That was, however, minor and didn't take much time. Similarly, setting up DKIM, SPF, and the like were necessary and ugly to do, but they didn't take much time.