diff --git a/core/admin/mailu/internal/templates/default.sieve b/core/admin/mailu/internal/templates/default.sieve
index 0e97c067..d5c28c8a 100644
--- a/core/admin/mailu/internal/templates/default.sieve
+++ b/core/admin/mailu/internal/templates/default.sieve
@@ -31,6 +31,6 @@ if spamtest :percent :value "gt" :comparator "i;ascii-numeric" "{{ user.spam_thr
 
 {% if user.reply_active %}
 if not address :localpart :contains ["From","Reply-To"] ["noreply","no-reply"]{
-  vacation :days 1 {% if user.displayed_name != "" %}:from "{{ user.displayed_name }} <{{ user.email }}>"{% endif %} :subject "{{ user.reply_subject }}" "{{ user.reply_body }}";
+  vacation :days 1 {% if user.displayed_name != "" %}:from "{{ user.displayed_name | replace("\"", "\\\"") }} <{{ user.email | replace("\"", "\\\"") }}>"{% endif %} :subject "{{ user.reply_subject | replace("\"", "\\\"") }}" "{{ user.reply_body | replace("\"", "\\\"") }}";
 }
 {% endif %}
diff --git a/towncrier/newsfragments/3260.bugfix b/towncrier/newsfragments/3260.bugfix
new file mode 100644
index 00000000..268da281
--- /dev/null
+++ b/towncrier/newsfragments/3260.bugfix
@@ -0,0 +1 @@
+Fix a bug preventing double quotes from being used in ooo messages