send-email: Describe 'ssl' and 'tls' in --smtp-encryption

Commit Message

Bagas Sanjaya Aug. 14, 2021, 9:20 a.m. UTC

The --smtp-encryption option accepts either 'ssl' or 'tls' value to
enable TLS connection. The latter can cause confusion (for example [1]),
because it means using STARTTLS, whereas users wanting SMTPS should set
to the former instead.

Describe these values, together with difference between SMTPS and
STARTTLS.

[1]:
https://lore.kernel.org/git/[e-mail]/T/#t

Signed-off-by: Bagas Sanjaya <[e-mail]>
---
 Documentation/git-send-email.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)


base-commit: 5d213e46bb7b880238ff5ea3914e940a50ae9369

Patch

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 3db4eab4ba..1207a6a8eb 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -176,8 +176,12 @@  Sending
 	for `sendmail` in `/usr/sbin`, `/usr/lib` and $PATH.
 
 --smtp-encryption=<encryption>::
-	Specify the encryption to use, either 'ssl' or 'tls'.  Any other
-	value reverts to plain SMTP.  Default is the value of
+	Specify the encryption to use, either 'ssl' (SMTPS or implicit
+	TLS) or 'tls' (STARTTLS or Opportunistic TLS). Any other value
+	reverts to plain SMTP. The difference between SMTPS and STARTTLS
+	is SMTPS uses encrypted connection from beginning of connection,
+	whereas in STARTTLS the existing connection is upgraded to use TLS
+	if SMTP server supports it. Default is the value of
 	`sendemail.smtpEncryption`.
 
 --smtp-domain=<FQDN>::