mail: use ciphers that are supported by android 4.4

dovecot/templates/conf.d/10-ssl.conf.j2

@@ -46,10 +46,13 @@ ssl_key = <{{ ssl_key }}
 ssl_dh_parameters_length = 4096
 
 # SSL protocols to use
-ssl_protocols = !SSLv3
+ssl_protocols = TLSv1.1 TLSv1.2 !SSLv3
 
 # SSL ciphers to use
-ssl_cipher_list = HIGH:!LOW:!SSLv2:!EXP:!aNULL:!MD5:!RC4:!SHA1
+#ssl_cipher_list = HIGH:!LOW:!SSLv2:!EXP:!aNULL:!MD5:!RC4:!SHA1
+#Supported Ciphers downto Android 2.3
+ssl_cipher_list = ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS
+
 
 # Prefer the server's order of ciphers over client's.
 ssl_prefer_server_ciphers = yes

postfix/templates/main.cf.j2

@@ -29,6 +29,14 @@ smtpd_tls_auth_only=yes
 smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
 smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
 
+#ciphers supported downto android 2.3
+smtpd_tls_mandatory_protocols = !TLSv1 !SSLv2, !SSLv3
+smtpd_tls_protocols = !TLSv1 !SSLv2 !SSLv3
+smtpd_tls_mandatory_ciphers=high
+tls_high_cipherlist=ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS
+smtpd_tls_eecdh_grade=ultra
+
+
 # See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
 # information on enabling SSL in the smtp client.
 smtpd_sasl_type = dovecot