Hide IMAP/POP3 software and version.

install/debian/8/dovecot/dovecot.conf

@@ -1,4 +1,5 @@
 protocols = imap pop3
 listen = *, ::
 base_dir = /var/run/dovecot/
+login_greeting = Mail Delivery Agent
 !include conf.d/*.conf

install/debian/9/dovecot/dovecot.conf

@@ -1,4 +1,5 @@
 protocols = imap pop3
 listen = *, ::
 base_dir = /var/run/dovecot/
+login_greeting = Mail Delivery Agent
 !include conf.d/*.conf

install/ubuntu/14.04/dovecot/dovecot.conf

@@ -1,4 +1,5 @@
 protocols = imap pop3
 listen = *, ::
 base_dir = /var/run/dovecot/
+login_greeting = Mail Delivery Agent
 !include conf.d/*.conf

install/ubuntu/16.04/dovecot/dovecot.conf

@@ -1,6 +1,7 @@
 protocols = imap pop3
 listen = *, ::
 base_dir = /var/run/dovecot/
+login_greeting = Mail Delivery Agent
 !include conf.d/*.conf
 
 namespace {

install/ubuntu/18.04/dovecot/dovecot.conf

@@ -1,6 +1,7 @@
 protocols = imap pop3
 listen = *, ::
 base_dir = /var/run/dovecot/
+login_greeting = Mail Delivery Agent
 !include conf.d/*.conf
 
 namespace {