Comment 0 for bug 1694610

New installs of postfix 3.1.4 on Zesty have broken lmtp configurations by default.

In /etc/postfix/master.cf, lmtp is called using the smtp binary, instead of the lmtp binary.

lmtp unix - - y - - smtp

However, the smtp binary runs in SMTP mode if called as "smtp" instead of "lmtp"

Quoted from https://git.launchpad.net/postfix/tree/src/smtp/smtp.c?h=stable/v3.1#n1330
"The process name, "smtp" or "lmtp", determines the protocol"

This is fixed in the Debian upstream in 3.1.4-7 (and by extension, Artful), but should probably be backported into Zesty as it breaks lmtp functionality.