Is it possible an email multipart Text/Plain and HTML both

[mijsoot]

Hello,

I was wondering if it was possible to make a multi-part sending like GMAIL does to avoid Spam ?
Like this :

Code Select Expand

MIME-Version: 1.0
From: Thierry Mijsoot <[email protected]>
Date: Wed, 3 Oct 2018 11:15:19 +0200
Message-ID: <CANoYYczT60YLU-cJawAq8-P5ah4SRk-jNuM5zo+2KWA9iJOMpA@mail.gmail.com>
Subject: test
To: [email protected]
Content-Type: multipart/alternative; boundary="000000000000f7115405774f7ac3"

--000000000000f7115405774f7ac3
Content-Type: text/plain; charset="UTF-8"

test *HTML*

--000000000000f7115405774f7ac3
Content-Type: text/html; charset="UTF-8"

<div dir="ltr"><div><span style="color:rgb(255,0,0)">test <b>HTML</b></span></div><div><b><br></b></div></div>

--000000000000f7115405774f7ac3--


My config:
Roundcube Webmail 1.3.6
Ubuntu 18.04.1 LTS
Linux version 4.15.0-29-generic (buildd@lgw01-amd64-057) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #31-Ubuntu SMP Tue Jul 17 15:39:52 UTC 2018

Thank you in advance for your lighting
Thierry

[alec]

Roundcube does exactly the same when you send a HTML message.