On Fri, Oct 13, 2017 at 01:18:00AM +0200, Johannes Schindelin wrote: > [who I had to cull from the To:/Cc: headers, as my mailer consistently > told me that there is no valid DNS record to route mail to > rpjday@xxxxxxxxxxxxxx, which *is* weird.] You are not the only one to mention this, so I did 60 seconds of digging. Turns out that the MX of crashcourse.ca points to a CNAME (mail.crashcourse.ca), which is explicitly forbidden by RFC 2181 (section 10.3). Some MTAs are picky about this and others are not (mine isn't, so I've added Robert back to the cc so he sees this). -Peff
