Re: [exim] exim can't handle 521 response from remote MX

On Sat, Sep 04, 2021 at 11:23:02AM -0400, Viktor Dukhovni via Exim-users wrote:
> FWIW, Postfix has always taken the SMTP status code from the last line
> of a multi-line server response, but as you noted there is no RFC
> requirement to do so, and the code is expected to not vary from line to
> line.

IMHO, this discussion should be a motive for Exim and Postfix developers
to add checks for consistency of SMTP status codes in multiline answers.

Inconsistent protocol messages are indicators of software bugs, so they
should lead to some attempts to work around (if possible) or switch to
status "communication impossible -- permanent failure".
--
Eugene Berdnikov