…you’ve replaced sendmail as your default MTA (in my case with postfix). Oh my word. Talk about stressful. At one point I thought I’d just obliterated a whole day’s worth of incoming mail because I kicked off fetchmail (thinking I was ready when I wasn’t), and postfix threw a wobbly. Thankfully it kept all the undelivered messages so after a few frantic minutes skimming the docs, hacking the config and one ‘postfix flush’ later, all my email reappeared. Phew.
I flatter myself that I can usually puzzle my way through most techie things, but email delivery systems are way more complex than I ever imagined. I had no idea what I was getting into when I started. Its still not working as I expected but I appear to be able to send email, so I think I’ll leave it until my palms stop sweating.