On Mon, 13 Nov 2017, John Stoffel wrote:
Could it be that you mail server is looking up and finding IPv6 addresses, but you don't have IPv6 enabled on your setup? Try forcing postfix to only use IPv4.
John, I will check. A new router was installed Friday and these delays showed up starting Saturday. I've put the old router back in service, but messages to one mail list are still delayed. Thanks, Rich