Comment by frumplestlatz
12 hours ago
I think can still do it, 30 years after I last had to. The trauma of debugging sendmail m4 config issues for hours while the company e-mail remained dysfunctional has permanently etched it into my mind.
EHLO example.com
MAIL FROM:<foo@example.com>
RCPT TO:<bar@example.com>
DATA
Subject: Hello, World
I have crawled through the depths of hell to deliver unto you this message.
.
Wietse Venema saved us all.
From and To should be repeated below DATA, those are the actual email headers. And From at least doesn't need to match MAIL FROM.
I haven't worked at sendmail or even anything e-mail related, and I can do that… just enough e-mail fixing as side work. Let's call it sysadmin calluses.
What made me stumble recently was having to talk LMTP to fix a mailman setup. Cheeky fuckers changed EHLO into LHLO for LMTP. (To avoid any mixups between the protocols, which is fair.)