diff --git a/core/dovecot/conf/dovecot.conf b/core/dovecot/conf/dovecot.conf
index 906b0e30..4ea4fc43 100644
--- a/core/dovecot/conf/dovecot.conf
+++ b/core/dovecot/conf/dovecot.conf
@@ -5,7 +5,11 @@ log_path = /dev/stderr
 protocols = imap pop3 lmtp sieve
 postmaster_address = {{ POSTMASTER }}@{{ DOMAIN }}
 hostname = {{ HOSTNAMES.split(",")[0] }}
+{%- if PROXY_PROTOCOL in ['all', 'all-but-http', 'mail'] %}
+submission_host = {{ HOSTNAMES.split(",")[0] }}
+{% else %}
 submission_host = {{ FRONT_ADDRESS }}
+{% endif %}
 {%- if SUBNET6 %}
 listen = *,::
 {% else %}
diff --git a/towncrier/newsfragments/3172.bugfix b/towncrier/newsfragments/3172.bugfix
new file mode 100644
index 00000000..b4c4e221
--- /dev/null
+++ b/towncrier/newsfragments/3172.bugfix
@@ -0,0 +1 @@
+Fix ooo/sieve replies when proxy protocol is in use