diff --git a/install/dist/lib/debian60.lib.php b/install/dist/lib/debian60.lib.php
index e24993056aad171ad90e9cad9dc9094997782299..57fb1934408364e2c2eef66eb757b4c099686d6d 100644
--- a/install/dist/lib/debian60.lib.php
+++ b/install/dist/lib/debian60.lib.php
@@ -109,6 +109,10 @@ class installer extends installer_base {
 			if(version_compare($dovecot_version,2.1) < 0) {
 				removeLine($config_dir.'/'.$configfile, 'ssl_protocols =');
 			}
+			if(version_compare($dovecot_version,2.2) >= 0) {
+				// Dovecot > 2.2 does not recognize !SSLv2 anymore on Debian 9
+				replaceLine($config_dir.'/'.$configfile, 'ssl_protocols = !SSLv2 !SSLv3', 'ssl_protocols = !SSLv3', 1, 0);
+			}
 		} else {
 			if(is_file($conf['ispconfig_install_dir'].'/server/conf-custom/install/debian6_dovecot.conf.master')) {
 				copy($conf['ispconfig_install_dir'].'/server/conf-custom/install/debian6_dovecot.conf.master', $config_dir.'/'.$configfile);
diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index f2c89fb0bf09c60a7aa657dbf4001aab3569545f..d339e5f87a51dd408123dd59436c781c69e6ce17 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -1270,6 +1270,10 @@ class installer_base {
 			if(version_compare($dovecot_version, 2.1, '<')) {
 				removeLine($config_dir.'/'.$configfile, 'ssl_protocols =');
 			}
+			if(version_compare($dovecot_version,2.2) >= 0) {
+				// Dovecot > 2.2 does not recognize !SSLv2 anymore on Debian 9
+				replaceLine($config_dir.'/'.$configfile, 'ssl_protocols = !SSLv2 !SSLv3', 'ssl_protocols = !SSLv3', 1, 0);
+			}
 		}
 
 		//* dovecot-lmtpd