Upgrading to Ubuntu 18.04 LTS seems to have broken mail delivery from the web server, ftp.eskimo.com. This does not affect webmail programs because they are all configured to talk directly to mail.eskimo.com rather than relaying, but it does affect scripts that you may have on your website to send mail to you.
Postfix broke in a way that some mail just disappeared into a black hole. Until I can figure out precisely how it broke (not easy as it is not logging any errors or bouncing the messages) I’ve installed null mailer, a very simple relay only mail server. However, even it is introducing random delays in delivery.
Just wanted you all to be aware of this and I am working towards a solution.