Allow a user to disable peer check when using TLS/STARTTLS

This is useful when developing and on Docker setups. Despite setting
encryption to null, if a server supports STARTTLS with a self-signed
certificate, the mailer try to upgrade the connection with STARTTLS.

.env.example.complete

@@ -79,6 +79,7 @@ MAIL_PORT=1025
 MAIL_USERNAME=null
 MAIL_PASSWORD=null
 MAIL_ENCRYPTION=null
+MAIL_VERIFY_PEER=true
 
 # Command to use when email is sent via sendmail
 MAIL_SENDMAIL_COMMAND="/usr/sbin/sendmail -bs"
@@ -372,4 +373,4 @@ LOG_FAILED_LOGIN_CHANNEL=errorlog_plain_webserver
 # IP address '146.191.42.4' would result in '146.191.x.x' being logged.
 # For the IPv6 address '2001:db8:85a3:8d3:1319:8a2e:370:7348' this would result as:
 # '2001:db8:85a3:8d3:x:x:x:x'
-IP_ADDRESS_PRECISION=4
+IP_ADDRESS_PRECISION=4

app/Config/mail.php

@@ -32,6 +32,7 @@ return [
             'encryption' => env('MAIL_ENCRYPTION', 'tls'),
             'username' => env('MAIL_USERNAME'),
             'password' => env('MAIL_PASSWORD'),
+            'verify_peer' => env('MAIL_VERIFY_PEER', true),
             'timeout' => null,
             'local_domain' => env('MAIL_EHLO_DOMAIN'),
         ],