From a6ed4a20312011db96d063c86ab079edae477daf Mon Sep 17 00:00:00 2001 From: Jean-Denis Vauguet Date: Fri, 12 Jun 2020 06:21:02 +0200 Subject: [PATCH] Updated A mail server's 101 (markdown) --- docs/content/a-mail-server's-101.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/content/a-mail-server's-101.md b/docs/content/a-mail-server's-101.md index d8acd6ca..a98480da 100644 --- a/docs/content/a-mail-server's-101.md +++ b/docs/content/a-mail-server's-101.md @@ -120,7 +120,7 @@ In many implementations, the mail server doesn't enforce TLS encryption, for bac - **docker-mailserver's default configuration enables and _requires_ Explicit TLS (STARTTLS) for Submission on port 587.** - It does not enable Implicit TLS Submission on port 465 by default. One may enable it through simple custom configuration, either as a replacement or (better!) supplementary mean of secure Submission. -- It does not support old MUAs (clients) not supporting TLS encryption. One may relax that constraint through advanced custom configuration, for backwards compatibility. +- It does not support old MUAs (clients) not supporting TLS encryption on ports 587/465 (those should perform Submission on port 25, more details below). One may relax that constraint through advanced custom configuration, for backwards compatibility. A final Submission setup exists and is akin SMTP+STARTTLS on port 587, but on port 25. That port has historically been reserved specifically for unencrypted (plain text) mail exchange though, making STARTTLS a bit of a misusage. As is expected by [RFC 5321](https://tools.ietf.org/html/rfc5321), docker-mailserver uses port 25 for unencrypted Submission in order to support older clients (Submission), but most importantly for unencrypted Transfer/Relay between MTAs.