diff --git a/towncrier/newsfragments/2650.bugfix b/towncrier/newsfragments/2650.bugfix
new file mode 100644
index 00000000..0e2ea011
--- /dev/null
+++ b/towncrier/newsfragments/2650.bugfix
@@ -0,0 +1 @@
+Tell roundcube to use UTF8 instead of 'UTF7-IMAP' when creating sieve scripts.
diff --git a/webmails/roundcube/config/config.inc.php b/webmails/roundcube/config/config.inc.php
index 3ced13e7..e07a8e64 100644
--- a/webmails/roundcube/config/config.inc.php
+++ b/webmails/roundcube/config/config.inc.php
@@ -25,6 +25,7 @@ $config['smtp_pass'] = '%p';
 
 // Sieve script management
 $config['managesieve_host'] = '{{ FRONT_ADDRESS or "front" }}:14190';
+$config['managesieve_mbox_encoding'] = 'UTF8';
 
 // roundcube customization
 $config['product_name'] = 'Mailu Webmail';