I was having some issues with my personal mail server (Postfix) and my phone (Android). The logs depicted the below issue: Jan 9 09:19:53 ip-11-222-23-223 postfix/smtpd[12345]: NOQUEUE: reject: RCPT from 12-13-14-15.abc.com.au[12.13.14.15]: 504 5.5.2 <localhost>: Helo command rejected: need fully-qualified hostname; from=<emailaddr kelvinism.com="kelvinism.com"> to=<emailaddr gmail.com="gmail.com"> proto=ESMTP helo=<localhost> </localhost></emailaddr></emailaddr></localhost> We can see here that the stock Android email client is doing a ‘helo localhost’. One part of my main.cf file specifies this:

You may have just read that I recently duct-taped my own walking treadmill. While driving home, I realised a reward might encourage me to keep going instead of simply crawling into bed with my laptop. Sydney’s winter is coming, and while it is not as cold as back home, it is colder than you might think. My house also seems to provide very little insulation (is reverse insulation possible?), so it can fall to 5-8 degrees Celsius inside.